“Saturday Night” filmmakers reveal how Billy Crystal supplied the most essential piece of “SNL” history

"[He was] the last person we expected to want to hold onto a memory of that night," director Jason Reitman tells EW.

To prep their Saturday Night Live biopic Saturday Night, writer/director Jason Reitman and co-writer Gil Kenan went straight to the source.

The filmmaking duo interviewed every living cast and crew member who was present for the comedy show's premiere broadcast on Oct. 11, 1975 — even the ones who seemed unreachable. "We spoke to scenic painters, costume designers, all the writing staff, all the performers who were still around," Kenan tells Entertainment Weekly.

Reitman, whose father Ivan ran in the same comedy circles as SNL's founders, notes that his existing relationship with the show's biggest figures made the process smoother. "I grew up with Chevy Chase, I grew up with Dan Aykroyd, and I met others like Billy Crystal along the way," the director says. "They're still giants of comedy, but I did know that they were human beings, and I think that gave me a little bit of an edge when it came to writing and in our conversations. I already saw 'em as people."

Related: Dylan O'Brien doesn't remember if he met Dan Aykroyd before playing him in Saturday Night

The Saturday Night research process began with the show's original architect, who still runs SNL to this day. "Lorne Michaels was the first conversation we had, which was really important because it opened the door for us to have the rest of the conversations, and we learned a lot of stuff that was never written down anywhere," Kenan explains. "I think Lorne has been able to focus his stories along the way, and simultaneously was the first to admit that memories change and that it's hard for anyone to decipher between the myths, the legends, and the truth," Reitman adds. "But the big thing for us was the moment he told us that he was originally going to host 'Weekend Update', and Chevy confirmed that."

Reitman sees Michaels' original intention of hosting the show's tentpole news segment — and his eventual resignation from it before the show went live — as the key to understanding the superproducer's personality. "That unlocked a lot for us, because there's a moment where you realize you're not the performer, you're the producer," he says. "You're not the kid, you're dad."

He continues, "We recognized that moment where you want to be one of the kids, but you have to be dad, and being dad on SNL means you run the house, and you have to fire some people. You have to choose what sketches don't get in, and you have to be a different kind of parent to each child who needs a different kind of parenting. So Lorne stepping down from 'Weekend Update' is a moment where he steps into the shoes of who will eventually be Lorne Michaels, the producer we all know."

The duo later interviewed Rosie Shuster, an essential SNL writer who was married to Michaels and dating Aykroyd during her early years on the show. "Both of us came away from that first call feeling like she was a key," Kenan says. "Her character felt so much like some of the voice of the show, and she's one of the funniest people we've ever talked to." Reitman also notes, "And she was able to lock in who Lorne was at 29 years old."

Related: Meet the SNL biopic cast: See Saturday Night stars next to real Lorne Michaels, Chevy Chase, George Carlin, more

Vital information and unexpected gems came from a multitude of SNL sources. Longtime writer Alan Zweibel provided extensively detailed anecdotes about the premiere, while the late production designer Eugene Lee supplied numerous drawings and his model of Studio 8H before his death last year. Another crucial contributor was Edie Baskin, the head photographer for the show who helped the filmmakers visualize SNL's production night. "Her visual imprint is still the identifying signature of the show, and she gave us this incredible walkthrough with her archive of photos from that night," Kenan says. "That helped us place people in the rooms where they were at certain moments before the show went live."

Ironically, one of the key figures in the duo's research was a performer who didn't make the cut for the actual SNL premiere. "Every time we would ask someone for a copy of the premiere script, nobody had it," Reitman says. "One person had it, and it was Billy Crystal, the last person we expected to want to hold onto a memory of that night."

Despite the fact that his act was ultimately chopped from the episode, the When Harry Met Sally star was the only person who held onto his script. "It happened so dramatically — we didn't know he had it," Kenan says. "It was one of the few in-person interviews we did, and we asked about the script as a sort of passing question like we did to everybody. And he said, 'Hang on a second,' walked into a study, came back out and just dropped it on the table in front of us."

Related: Saturday Night fact check: The true stories behind movie's wildest tales of SNL premiere

Crystal didn't let the filmmakers forget about his unfortunate fate on premiere night. "He flipped through and pointed to a blank page and said, 'That's where I was supposed to be!'" Reitman recalls. "And he allowed us to scan it. Gil immediately scanned the whole thing into his iPhone. And as a result, every time the characters in our movie are holding a script of any kind, it's Billy's script."

However, Reitman and Kenan never wanted their intensive research to yield an exact beat-for-beat cinematic account of every single detail that transpired on premiere night; rather, they sought to gather as much information as possible to most accurately depict the atmosphere, interpersonal dynamics, and intense emotions leading up to the first SNL ep. "It's been really interesting talking to journalists about the movie this week, every journalist wants to know what really happened that night," Reitman says. "And for us, that was never the goal. A movie is not about what happened, a movie is how it makes the audience feel. And what we wanted to capture was what did it feel like moments before this went to air if you were one of the people standing on the floor."

Reitman continues, "Something that Gil and I are both mutually interested in is what does it feel like in the room when genius happens? If you could have sat in a room with Mozart working, would you feel something happening? Would the temperature change in the room, or would it just be like, yeah, 'I'm with some Austrian dude who's playing piano'? SNL was a groundbreaking, life-changing cultural shift for us both, so we've always wondered what it feels like right before this show goes to air and everything we know as comedic television changes."

Related: How to watch the first-ever Saturday Night Live episode from 1975

And although Saturday Night paints some of its figures in a fairly negative light — NBC execs, especially — the filmmakers experienced no resistance from the network or anyone who currently works on SNL. "There was that one day where we found a dead peacock in our bed, but otherwise it was all good," Reitman jokes. "And that could have been something else. There's a lot of people who would do that."

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The filmmakers also say that several of the SNL alums depicted in the movie have already watched it, including Chase, Zweibel, Crystal, Garrett Morris, Laraine Newman, and Howard Shore. "The response has been genuinely favorable," Reitman says. "Everyone's been lovely, it's the honest to God truth. They've been really sweet."

Kenan adds, "I hope that what they see in it is that we made this with a spirit of absolute love for the world of comedy that they helped create. It's really cool that there's so many of them out there still working and still making stuff that we're into, because we feel really indebted to all of 'em."

Saturday Night is now playing in theaters.

Read the original article on Entertainment Weekly.