“This was the most complicated movie I’ve ever made by a country mile,” admits Saturday Night director Jason Reitman. “What we wanted to do was create organized chaos, but in order to create that chaos, it’s like putting on a ballet. A ballet where you have 80 background actors, 80 speaking roles, and these shots that go on for five minutes. The chaos has to be choreographed down to the inch so that everything happens just at the right moment, and every character’s doing the right thing, and it feels like a genuine, natural place.”

Reitman, speaking during a virtual press conference, reflects upon recreating a moment that changed popular culture. Saturday Night considers what happened at 30 Rockefeller Plaza in the 90-minutes before the inaugural episode of Saturday Night Live went to air. It’s a laugh-a-minute backstage dramedy about taking a risk in the increasingly risk-averse world of showbiz. The Altman-esque comedy has a sprawling ensemble and a medley of overlapping dialogue as Lorne Michaels (The Fabelmans’ Gabriel LaBelle) deals with a Murphy’s Law catalogue of crises before showtime.

“Jason would have a whiteboard with a marker drawing where we’re going, like we’re playing American football and we’re about to attack each other,” explains LaBelle. “These are stories of the first five years with that cast, I just wanted to find out how Lorne knew all of these people, how he collected them to that show. How he knew Gilda Radner and Dan Aykroyd from improv in Toronto. How he taught Dan Aykroyd improv when Dan was 16 and gave him his first television appearance on The Hart and Lorne Terrific Hour for the CBC in 1974. And how he met Michael O’Donoghue, Chevy Chase.”

A new generation of actors joins LaBelle in breathlessly recreating this Big Bang moment for comedy greats. Dylan O’Brien plays Aykroyd with gusto, while Horizon’s Ella Hunt brings Gilda Radner back to life, and May December’s Cory Michael Smith proves a scene-stealer as Chase. Newcomer Matt Wood enjoys a breakthrough turn as John Belushi, perhaps the biggest source of backstage drama. Fargo Emmy winner Lamorne Morris plays Garrett Morris (no relation) with Kim Matula and Emily Fairn rounding out the comics as Jane Curtain and Laraine Newman, respectively.

While seeing this cast riff on iconic SNL material turns the wheels of the nostalgia factory—the origin story of Aykroyd’s Julia Child bit is particularly fun, as is Chase’s mastery of “Weekend Update”—Michaels’ dizzying romp around the stage gives audiences a taste of the creative ingredients that clicked to make comedy magic. Michaels juggles real-time decisions as he tours the set, engaging in Sorkin-esque walk-and-talks with cast and crew. But as Michaels puts out fires, reassures NBC executive Dave Tebet, and endeavours to get Belushi to sign his contract, Saturday Night frequently inspires more anxiety than laughs.

“What was important to [co-writer] Gil [Kenan] and I was evoking a feeling,” explains Reitman.” What is it like when it’s 60 minutes before airtime and the show is just coming together, and you don’t know how you’re gonna actually make it. Everyone in [media] knows what it’s like when they start doing the countdown. When they go, ‘We’re 30 seconds to air’ and everyone tightens up. We wanted to capture that feeling in a movie so that the audience could feel what is it like when your adrenaline is soaring and this group of misfits comes together and coalesces to create something great.”

Reitman says that he and Kenan undertook extensive interviews to capture that mood. “We’re pulling memories from the weeks before, the weeks after, to create 90 straight minutes that let you know how it feels to be in the room.” Reitman says they interviewed every living person they could find who was there on October 11, 1975.

The Saturday Night director says that entailed making a massive script with layers of dialogue. “There was primary dialogue, which was telling you one story,” explains Reitman. “Then there was the next set of characters who would walk by, who would tell you another story. Then there’s the physicality of the people who were doing something in the background. And then there was deep background action. In every scene, we were trying to tell nine different pieces of story at the same time.”

Drawing upon so many stories enlivens Saturday Night with a roller coaster of seemingly farfetched beats. But Reitman says they’re all real accounts pieced together with the oral history that informed the script. “Stealing a lighting director from another floor. The sound system going out, and then borrowing the system that was used in Madison Square Garden the night before is real,” explains Reitman. The director notes that the on-set bricks, which form a visual ticking clock as a production designer Leo Yoshimura (Abraham Hsu) lays real bricks on the stage, are also real. “Leo getting punched out in the alleyway: real. Milton Berle [J.K. Simmons] pulling out his penis: real. It’s all real. That’s what made it delightful. It also just became a very complex job of writing in that we had to braid together these stories in 90 continuous minutes.”

Amid all the interviews, though, Reitman says that he and Keenan found Saturday Night’s coagulant: Michaels’ relationship with his wife, writer Rosie Shuster (Rachel Sennott). Michaels faces an underlying dilemma when the control room asks if they should credit Rosie as “Michaels” or “Shuster.” Michaels puts off making the call, which becomes a recurring query amid all the noodles being thrown at 30 Rock’s walls. He knows that decision means confronting the reality of their relationship, which thrives creatively, but wheezes romantically.

“Rosie made us laugh more than any other person we spoke to. She’s incredibly sharp. Her writing is sophisticated and interesting,” says Reitman. “Gil and I immediately fell in love with the nuanced, complicated love relationship between Rosie and Lorne.” Reitman says that complicated relationships are an interest point of his work going back to Up in the Air.

“In Rosie and Lorne, I saw two people who were towards the end of a marriage, still loved each other, still supported each other,” says Reitman. “They both knew that they were their creative best selves when in the room together. And I like that they knew how to co-exist. That she could be dating someone on the show, they could be working together on the show. Their relationship could be evolving as it had two or three times already prior to that.”

LaBelle adds that the playful dynamic with Sennott was a highlight in capturing the feeling before showtime. But the Vancouver native also relished revisiting the film’s Canadian connections, which helped make Saturday Night a hometown favourite at the Toronto International Film Festival in September. “They fell in love with comedy together growing up in Toronto, and they went all over the place together. They wrote in college together, they wrote for the CBC radio. And they went to Los Angeles and worked on pilots together, and various television shows,” observes LaBelle. “Although they may be in a strange separation purgatory of where their relationship is headed, they’re still best friends. He still needs her by his side to guide him because he can’t be vulnerable around many other people in that room.”

That chemistry between LaBelle and Sennott makes Saturday Night’s many moving parts click, just as Michaels and Shuster made the magic happen decades ago. “I think all too often, we think of marriage as a binary thing. That’s how it appears on screen all the time,” says Reitman. “You’re married and then you hate each other and then you love each other. They had something far more beautiful and complex than that. They discovered that their creative relationship was far more important than their sexual relationship. Interestingly, I found the same thing about Gabe and Rachel. There was something that happened when the two of them were in scenes together: there was this chemistry that happened that they brought the best out of each other.”

Saturday Night opens in theatres Oct. 4.