Leonardo DiCaprio created and improvised one of the most memorable moments in Quentin Tarantino’s Once Upon a Time in Hollywood, it has been revealed.

Quentin Tarantino told the story this weekend at a special event at his Los Angeles theater, the New Beverly Cinema, where he was joined in a post-screen Q&A session by Leonardo DiCaprio, Brad Pitt, and Margot Robbie from Once Upon A Time In Hollywood. When Tarantino was asked how the trailer freak out sequence came together, he said that it all started with a message from Leonardo DiCaprio:

“It wasn’t in the script actually, so we never rehearsed it or anything,” Tarantino said. “Leo had a whole thing. At some point it was like, ‘Look, I need I need to fuck up during the “Lancer” sequence, all right? And when I fuck up during the “Lancer” sequence, I need to have a real crisis of conscience about it and that I have to come back from that to some length.’”

The inclusion of the Lancer sequences  was partially because he wanted to basically smash two genres in one: make a tiny western inside of his bigger movie about Hollywood. Rick Dalton mucking things up would mean mucking up Tarantino’s western. However, after the plan was put into action on set, the director recognized that Leonardo DiCaprio was right:

“My immediate response is, ‘What are you going to f*ck up my western sequence? That’s my western, alright? I get two for one with this movie! I’m trying to sneak a Western in here when nobody’s fucking looking. Don’t fuck it up!’ And so almost like we did with him fucking up his hand in Django where it was like, ‘Well, I don’t know if I want to do that.’ So we did the Lancer scene without the f*ck up, and then we did it with the f*ck up. And then once we did it with the f*ck up it was just so amazing, alright, that of course we’re going to use it.”

Tarantino then developed DiCaprio’s concept and created the in-trailer outburst, based on Robert De Niro’s legendary performance in Taxi Driver.

“I think I described it exactly this way, I think we shot it exactly this way — It’s gotta be like Travis Bickle when he’s in his apartment by himself,”  Tarantino remarked, echoing DiCaprio’s instruction during production.

The setup was straightforward. Everything would be unscripted, and the scenario would be shot from a single perspective – a medium shot from the far side of Rick Dalton’s trailer. Quentin Tarantino intended for three takes, each spanning the length of the reel, with the intention of editing everything together in post-production as jump cuts.

DiCaprio began to exhibit some hesitation after they were both in agreement, but Tarantino was there to help the actor through with his knack for filthy language, as is to be anticipated.

“He’s like, ‘Well, what should I say?’ I go, ‘Well, you should improvise. I want you to improvise it, but I’ll come up with things to be flipped out about.’ So I came up with about four or five or six things that he could obsess on and go nuts over. But then it was going to be him doing it. So if ever he runs out of… ‘Get pissed off about Jim Stacy.’ [As Rick Dalton] ‘Oh that fucking Jim Stacy just sitting up there watching me, and thinking he’s so fucking hot. He couldn’t be a fucking wrangler on my fucking TV show!’ [As himself] ‘Talk about the little girl.’ [As Rick Dalton] ‘And that fucking little girl! She’s sitting there…!'”

DiCaprio was worried about the improvisation, according to the director. He remarked, “I’ve never seen him so nervous as on the day,” he said.

DiCaprio claims that he drew on his own personal experience as an actor who has endured bad days. “I’ve definitely had days like that,” he said. “I don’t think I’ve ever flipped out quite like that.”

While Leonardo DiCaprio’s Rick has a lot of lines in both his personal life and his acting in movies within movies, Margot Robbie’s Sharon Tate has a lot less.  But it’s Robbie’s non-verbal performance that makes her such a commanding presence on screen. “I don’t think I’ve ever felt so transported as I did on Quentin’s set because number one, everything’s practical. There’s not just the foreground of props and setting and then the rest is going to be blue screen, green screen, we’ll do it later. It’s all 1969 around you. And as far as you can see down the street, there’s a row of cars from the 60s,” she said.