Among all of Oscar-nominated writer and director Jason Reitman's many achievements, he still counts a very short stint at Saturday Night Live as a favorite.

"One of the greatest weeks of my life," Reitman recalls of his brief time working at the legendary sketch show, while speaking to Entertainment Weekly at the Toronto International Film Festival, where he's promoting his upcoming feature film, Saturday Night, about the show's creation.

"I was lucky enough to guest write at Saturday Night Live back in 2008," he tells EW. "Right after Juno, I got the chance to go in and spend one week. I got a sketch on the air."

Getty;SNL/Youtube

Reitman served as a guest writer for an Ashton Kutcher-fronted episode on April 12, 2008. The sketch he got on the show was a three-part pre-recorded short called "Death by Chocolate," a literal take on the saying, in which a murderous chocolate bar (Kutcher) stabs, shoots, and chainsaws people to death.

The electricity in the room during the live show made a huge impact on Reitman, who is trying to capture that sense of "organized chaos," as he calls it, in his new film, which opens in select cites later this month before its wide release on Oct. 11.

"That feeling, minutes before, when they're still painting the set, and they're still hemming the dresses, and they're pining the wigs, and it feels like there's no way that this show could possibly get on air," Reitman describes. "We wanted to capture that energy and exhilaration when a cast comes together, a cast and crew, when they all come together, and you just somehow make it across the finish line."

Hopper Stone/Sony

Saturday Night focuses on the intense 90 minutes leading up to SNL's first-ever broadcast on Oct. 11, 1975, fronted by a rag-tag group of mostly unknown comedians who went on to become legends: Chevy Chase (Cory Michael Smith), John Belushi (Matt Wood), Dan Aykroyd (Dylan O'Brien), Gilda Radner (Ella Hunt), Garrett Morris (Lamorne Morris), Jane Curtin (Kim Matula), and Laraine Newman (Emily Fairn). Gabriel LaBelle, who played a dramatized version of teenage Steven Spielberg inThe Fabelmans stars as 30-year-old SNL mastermind Lorne Michaels.

Joining his director at TIFF, LaBelle tells EW that he's impressed by the way Reitman and co-writer Gil Kenan managed to give character arcs to more than just the leads of the film, which has a whopping 80 speaking parts.

"Every single character has a beginning, middle, and end, and everyone stands out, and every character pops and shines, and all the actors give them such beautiful nuance," LaBelle says, predicting each of the film's characters is "going to be someone's favorite part of the movie because it's so rich and so detailed."

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Speaking of detailed, for the movie, Reitman obtained the original blueprints of Rockefeller Center and leaned on the memories of those who were there at the time to build a replica of Studio 8H, including the SNL set and backstage areas that viewers have seen peeps of on air over the years. They did such a good job recreating the studio that actual SNL staffers were able to maneuver the set as if it was the real deal.

"We had an incredible attention to detail," Reitman says. "We had people who have worked on Saturday Night Live who visited our set as guests, and they knew exactly where to go. They could walk down the hallway, go up the stairs, if you want to get to Lorne's office, they'd be like, 'Yeah, I know how to get there, you don't have to tell me. I know where I'm going.'"

Fans can see for themselves when Saturday Night hits theaters in Los Angeles, New York, and Toronto on Sept. 27, followed by a limited release on Oct. 4, and a wide release on Oct. 11.

Listen to Reitman and LaBelle's full interview on The Awardist podcast below.

With reporting by Gerrad Hall.