Rachel Sennott Says Saturday Night Role Is Her 'First Time Being Chill' in a Movie: 'I'm Always Having a Panic Attack' (Exclusive)

Saturday Night gave Rachel Sennott a chance to play a "chill" character — for once in her acting career.

Speaking exclusively with PEOPLE about the film, which chronicles the hour leading up to the first live episode of Saturday Night Live in 1975, Sennott, 29, spoke about getting to know Rosie Shuster — the original SNL writer who she portrays in the film and the then-wife of the show's creator Lorne Michaels.

"I got to talk to Rosie, and she's amazing," Sennott said of the comedian, who wrote for SNL in the '70s and '80s. "She's so cool, and smart, and funny, and I think I'm going to meet her in person for the first time at the premiere."

"Just talking to her on the phone, of course there's still pressure," she said, recounting her first time speaking with Shuster. "But more than anything, I was just excited. Because I was like, I want everyone to know [about her]."

For Sennott, sharing Shuster's story with audiences who may not have known about her role in making SNL so successful was one of the most exciting parts of making the film — along with getting to play a character who's not easily frazzled.

"This is my first time in a movie being like chill," she joked. "I'm never chill. I'm always having a panic attack. And in real life, I'm always having a panic attack."

"So, it's so freeing to step into someone who's so confident, and in control. And so, I hope she likes it, and feels seen. But I just wanted to share her story with people, because I feel like she's such an integral part in making SNL what it is today," the Bottoms actress continued. "And I don't know if everyone is familiar with her, so, I'm excited for them to see that."

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Saturday Night takes place during the 90 minutes before SNL went live for the first time on Oct. 11, 1975. Written by Oscar-nominated director of Juno Jason Reitman and Gil Kenan, the movie is based on interviews conducted with the cast members, writers and producers of the iconic TV pilot.

The film stars a number of young actors as famous SNL alumni, including The Fablemans' Gabriel LaBelle as Lorne Michaels, Dylan O'Brien as Dan Aykroyd, Cory Michael Smith as Chevy Chase and Lamorne Morris as Garrett Morris.

Tons of other stars make an appearance in the film as classic SNL comedians — including the late Philip Seymour Hoffman’s son Cooper Hoffman as Dick Ebersol, Jon Batiste as musician Billy Preston, Willem Dafoe as David Tebet and J.K. Simmons as Milton Berle. Ella Hunt as Gilda Radner, Emily Fairn as Laraine Newman, Kim Matula as Jane Curtin, Matt Wood as John Belushi, Nicholas Podany as Billy Crystal, Nicholas Braun as Jim Henson and Kaia Gerber as Jacqueline Carlin.

Saturday Night is now playing in select theaters and opens everywhere Oct. 11.