“Saturday Night” is a fly-on-the-wall dramatization of the tense, chaotic 90 minutes leading up to the first broadcast of “Saturday Night Live.” Directed by Jason Reitman, the film depicts the rebellious group of writers and performers who helped create a comedy institution that has defied all predictions by enduring on NBC for half a century.

Many of the players will be familiar to “SNL” fans, starting with wunderkind producer Lorne Michaels (Gabriel LaBelle) and original cast members like Chevy Chase (Cory Michael Smith), Gilda Radner (Ella Hunt) and John Belushi (Matt Wood). But the film also looks at some lesser-known figures who will likely send viewers down a Wikipedia hole, including writer Rosie Shuster (Rachel Sennott) and NBC late-night executive Dick Ebersol (Cooper Hoffman).

Written by Reitman and Gil Kenan, “Saturday Night” plays up the possibility that the show we now know as “Saturday Night Live” almost never happened, and were it not for the audacious, countercultural ethos of its creative team, could easily have gone the way of “Saturday Night Live with Howard Cosell,” a live and similarly-named variety show on ABC that launched weeks earlier but was canceled by January 1976. (“SNL” officially added the “Live” for Season 3, in 1977.) The film includes many colorful details about what may or may not have happened behind the scenes at 30 Rockefeller Plaza from 10 to 11:30 p.m. on the night of Oct. 11, 1975, including an X-rated cameo by Milton Berle and a plot by NBC executives to preempt the premiere with a rerun of “The Tonight Show.”

Kenan and Reitman began their research for the project at the top — by calling Michaels and telling him the rough idea they had for a movie about the first episode of “SNL.” He gave the project his blessing. From there, executive producer Erica Mills began to track down everyone who might have been present that night. This was 2020, and most of the interviews were conducted over Zoom. “By the end, we spoke to over 40 folks who worked across the board on the show from Lorne, his cousin, Neil Levy, who was a [production assistant], to the production designer, art director, costume designer and to every cast member and writer who was still around at the time of our writing,” Kenan said. (Three of the people interviewed have since died.)

They also cast a wide net in terms of written material, drawing from books and contemporaneous press accounts. “The good news for us is that almost right from the beginning, the show became something that people like to write about. There is a New Yorker think piece about the cultural relevance of the show a few weeks into its run,” Kenan said.

They spent four or five months outlining, researching and doing “historical spelunking” before they began to write, Kenan said. At one point, they even made maps indicating where everyone was in the building that night. “It almost felt like we were solving a murder,” he said.

But they knew early on that they would take some liberty with the facts. ”The more we spoke to folks, the more we got a sense that there was a clear narrative arc for us. It was going to be about the mounting obstacles that were cascading in Lorne’s path in the 90 minutes leading up to the first ‘Live, from New York!’ But the stories we were hearing from folks were sometimes happening days or weeks before or after that first episode,” Kenan said. “We were creating something that was embracing a spirit of anarchic storytelling that allowed that show to make it on the air.”

As it opens Friday in wide release, here’s a look at the real stories behind the drama in “Saturday Night.”

Lorne Michaels in 1977, left, and Gabriel LaBelle as Michaels in “Saturday Night.”

(NBCUniversal via Getty Images; Hopper Stone/Sony Pictures Entertainment)

How close was the show to being a disaster?

In “Saturday Night,” the show is plagued by technical difficulties up until the last minute. A lighting rig crashes to the ground during dress rehearsal. A couch catches fire. The brick floor of the stage is unfinished. The situation is so precarious that nervous NBC executives have a repeat of “The Tonight Show” ready to roll.

The atmosphere behind the scenes was indeed rather chaotic.

”That all happened the first night — the sofa catching on fire and getting replaced with the one from the writers’ room. That is all stuff we got from the interviews,” Kenan said. “Some of the wildest moments that just feel like they’re writerly flights of fancy are actually correct,” he said.

The show was filmed at Studio 8H, a long-neglected space designed for radio broadcasts that reportedly hadn’t hosted a live TV show since 1958. Michaels “was aghast at the condition” of the studio, according to “Live From New York: An Uncensored History of Saturday Night Live,” the dishy book by James Andrew Miller and Tom Shales.

“We almost didn’t get on the air, because dress rehearsal went so poorly,” associate producer Craig Kellem recalls in the book. But it was Michaels, not the network, who wanted a back-up plan in place. “I remember Lorne seriously asking the network people — or having me ask them — to have a movie ready to go, just in case. And I don’t think he was kidding,” Kellem says.

The producer also had very specific ideas about the authentic look he wanted for the set, and, as production designer Eugene Lee told Vanity Fair in 2016, he was laying bricks on the stage a few hours before comedian George Carlin, the show’s inaugural host, walked on them. Production designer Akira “Leo” Yoshimura also told the “Saturday Night” filmmakers that, if you look closely at the opening of the first episode, “You can see the light panels swing as the show goes live.”

NBC’s head of talent Dave Tebet (portrayed by Willem Dafoe) was supportive of the show, according to Michaels in “Live From New York.” But he was also concerned that if Carlin appeared wearing a T-shirt, he would alienate already reluctant affiliates. So they compromised by putting Carlin in a T-shirt and suit. Ultimately, only about two-thirds of the network’s affiliates carried the first broadcast.

Was Johnny Carson mad about “Saturday Night”?

In “Saturday Night,” Michaels receives a phone call from an irate Carson, who evidently feels threatened by the arrival of a younger, edgier late-night show at NBC.

But the opposite is true: As recounted in “Live From New York,” NBC decided to develop a late-night show to air on Saturday nights in order to placate Carson. For years, NBC affiliates had aired repeats of “The Tonight Show” on weekends, but Carson wanted to use them during the week so he could take more time off. In 1974, network president Herbert Schlosser, keen to accommodate his biggest star, ordered what would become “Saturday Night Live.”

It is true that Carson, who turned down repeated invites from Michaels to host “Saturday Night Live” over the years, was not a fan at first. “He was openly appalled at some of its more outrageous gags,” according to “Live from New York.” It’s also true that Chevy Chase was almost immediately seen as a rising comedy star — and potential successor to Carson.

Rosie Shuster in 1979, left, and Rachel Sennott as Shuster in “Saturday Night.”

(Ron Galella Collection via Getty Images; Hopper Stone / Sony Pictures Entertainment)

Who was Michaels’ first wife and what did she do on the show?

The quiet hero of “Saturday Night” is Rosie Shuster (Rachel Sennott), Michaels’ first wife and an accomplished comedy writer in her own right. Portrayed as an unsung comedy genius and skilled talent whisperer with a gift for handling the show’s mercurial stars, she is a quintessential 1970s woman — in an open relationship but unsure whether she wants to use her married or maiden name in the credits.

Shuster and Michaels grew up in the same Toronto neighborhood and reportedly became an item after he followed her home from school in order to meet her famous father, Frank Shuster, of the comedy team Wayne and Shuster. “There was not a pubic hair in sight when he arrived on my doorstep,” Shuster recalls in “Live From New York.” “I guess he was struck by my mojo or whatever.” The couple married young and worked together throughout the 1970s, including on Canadian TV and “The Lily Tomlin Show” for ABC. She is listed variously in the “SNL” credits as “Rosie ‘Bud’ Michaels,” “Rosie Apple” and “Rosie Shuster.”

Shuster, often writing with Anne Beatts, helped shape a number of memorable characters and recurring sketches, including elderly commentator Emily Litella (played by Radner), male prostitute Fred Garvin, (Dan Aykroyd), pervy babysitter Uncle Roy (Buck Henry), and Lisa and Todd, a.k.a. the Nerds (Radner and Bill Murray). She won two Emmys for writing on “SNL,” but still found the boys club atmosphere oppressive. In “Saturday Night,” she is especially deft at wrangling an already difficult Belushi, but in reality, he sometimes refused to star in sketches written by her and Beatts.

“It was hard getting writing from a female point of view accepted,” she told the Associated Press in 2021.

The movie accurately captures the messy, overlapping romantic entanglements during the show‘s early years, along with the unconventional nature of Shuster and Michaels’ marriage. In “Live From New York,” director John Landis recalls getting a tour of the “SNL” offices from Belushi and being struck by a “very sexy girl” who walked by. Belushi reportedly told him, “That’s Rosie Shuster. She’s Lorne’s wife and Danny’s girlfriend.” Paula Davis, a young assistant, remembers going to Shuster’s apartment on an errand and finding Aykroyd in her bed. “I was totally surprised, because last I knew, Aykroyd was with Laraine [Newman].”

Michaels and Shuster divorced in 1980, right around the time they both left “SNL.” But both later returned to the show. Shuster helped Dana Carvey devise his Church Lady character at “SNL,” and also wrote on “The Larry Sanders Show” and the sitcom “Square Pegs.”

Reitman and Kenan spoke to Shuster for the film, and found the interview especially illuminating. “Both of us felt like another key had been handed to us, because she was so compelling,” Kenan said. “There was a character here who was underrepresented in the written record of the early years of the show, but clearly had a comic voice that was over-indexing.”

Was Michaels really planning on anchoring “Weekend Update”?

Yes, and it’s not nearly as implausible as it seems in “Saturday Night.”

In 2014, Michaels told Deadline he briefly considered being a performer on “SNL.” He had already been the star of his own variety show on Canadian television, “The Hart and Lorne Terrific Hour,” where he anchored “Weekend Update”-like segments spoofing the news. (He also made a mockumentary about a drought that had supposedly decimated the country’s hockey-puck trees.)

But as the show got closer to launch, Michaels “began to realize that I didn’t think I could be the person who cut other people’s pieces and left my own in,” he told Deadline. “So I gave ‘Weekend Update’ to Chevy, who was not a cast member, but a writer at the time.”

It’s unlikely that this switch happened minutes before the show debuted, as the movie portrays. According to “Live From New York,” Chase appeared as a “fatuous anchorman” in screen tests weeks before the premiere.

Because Chase only signed a one-year contract as a writer, and repeatedly declined to sign an additional contract as a performer, he was free to leave the show after little more than a single season, when cast member Jane Curtin succeeded him on “Weekend Update.”

Michaels, meanwhile, has made cameos as himself throughout his run on “SNL,” in sketches playing off his image as the show’s wise impresario.

Chevy Chase in 1975, left, and Cory Michael Smith as Chase in “Saturday Night.”

(Silver Screen Collection / Getty Images; Hopper Stone / Sony Pictures Entertainment)

Did Billy Crystal get cut from the premiere?

Yes, one of the biggest comedy stars of the last half-century did, in fact, get bumped from the lineup at the last minute.

According to “Live From New York,” Michaels had seen Crystal perform at Manhattan comedy club Catch a Rising Star months earlier and recruited him to do a piece on the first show. It was an African safari sketch, which ran about six minutes long and included sound effects created by crunching potato chips. After sitting around all week at rehearsals with little direction, Crystal performed it at a Friday run-through — and it killed.

But Lorne sent a note later saying Crystal could have two minutes total. “I didn’t have a two-minute thing I could plug into the show,” Crystal says in “Live From New York.” “So we had a big dilemma.” Before the Saturday dress rehearsal, Crystal’s manager Buddy Morra confronted Michaels and urged him to cut Andy Kaufman instead. It backfired. Michaels kept Kaufman because “there was nothing else like him in the show,” he says.

Crystal was sitting in the lobby with Radner, waiting for dress rehearsal to begin, as this confrontation unfolded. Morra came down and told his client he had been cut and that they needed to leave. “I was totally confused about the whole thing,” says Crystal, who was then an up-and-coming comedian living on Long Island. “I didn’t want it to look like I was the guy who stormed off the show.”

“After that, things weren’t great for me for a while,” he says in “Live From New York.” Crystal eventually became a cast member, for a single season, from 1984 to 1985.

“He is arguably one of the most successful comic storytellers of our time, but he was cut for time,” said Kenan, who interviewed Crystal about the experience and was delighted when the actor pulled out an original copy of the teleplay of the first episode, which included a cut sketch about Alexander the Great’s high school reunion and had, until then, been impossible to find. ”It’s one of the emotional touchstones for me, for our storytelling on this film,” Kenan said.

Did Michaels hire writer Alan Zweibel minutes before the show premiered?

In “Saturday Night,” Michaels leaves 30 Rock in search of a wayward Belushi and pops into a nearby bar, where he meets an aspiring comedy writer named Alan Zweibel. Michaels hires him on the spot to write for the show, which is just minutes away from premiere.

In reality, Michaels did hire Zweibel after scouting him in a comedy club, but it happened well before “SNL” premiered. At the time, Zweibel was working at a deli in Queens and selling jokes to Catskills comics for $7 a pop. As he describes in “Live From New York,” he had taken all the material that was too risqué for them and turned it into a stand-up set, with the goal of landing a TV job. He and Crystal lived near each other on Long Island and would drive into the city to perform at various clubs.

One night, a guy sat down next to him at the bar. It was Michaels, who was scouting talent. Zweibel went home to Long Island, spent several days writing up every joke he could think of — more than a thousand in total — then brought the “phone book” of one-liners to an interview with Michaels at the Plaza Hotel. He told Michaels he was making $2.75 an hour at the deli. Michaels said he could match it and offered him a job.

What Zweibel considered the No. 1 joke in his legendary “phone book” did make it into the first show, and, as portrayed in “Saturday Night,” was his lone contribution to the historic episode: It was a crack about the post office issuing a 10-cent stamp commemorating prostitution. “But,” as Chase quipped in “Weekend Update,” “If you want to lick it, it’s a quarter.”

Milton Berle in 1979, left, and J.K. Simmons as Berle in “Saturday Night.”

(Reed Saxon / Associated Press; Hopper Stone / Sony Pictures Entertainment)

Did Milton Berle really flash his penis to people on the show?

One of the more outrageous scenes in “Saturday Night” apparently did happen — but not quite as depicted. “It didn’t happen that night, but Berle was famous for letting it all hang out,” said Kenan. Mr. Television hosted “SNL” in 1979, and his hostile, controlling behavior and dated, overly broad shtick left a vivid impression with many who were there, according to numerous accounts in “Live From New York.”

Also leaving an impression? A certain appendage.

In the book, Zweibel recalls being in Berle’s dressing room, where the legendarily well-endowed comedian was wearing a short bathrobe. ”It’s so weird I’m here talking to you, because for years I was writing jokes about your [penis],” Zweibel recalls telling Berle, who reportedly asked Zweibel if he’d like to see it and, without waiting for a response, whipped out “this anaconda” and laid it on the table. “It was enormous,” Zweibel says. Berle asked what he thought of it, to which Zweibel replied, “It’s really nice” — just as Radner opened the door to the dressing room.

In “Saturday Night,” Berle flashes not Zweibel, but Chase, who is already being touted as the show’s breakout star and has an ego nearly as large as Berle’s member.

“Thematically, it was a perfect way to represent the confidence of the institution of entertainment that our young comics were going up against,” said Kenan.