There are many standout moments in Quentin Tarantino’s lovely 1969-set Once Upon a Time in Hollywood, but there’s one in particular that fans were already anticipating from the trailer: we see Leondaro DiCaprio’s rugged Rick Dalton beating himself up in his trailer for messing up his lines on the set of Lancer. The scene was a hilarious standout in the marketing, and in the context of the film it’s still funny but also takes on a newfound sadness knowing how seriously Dalton takes his acting craft, and how lonely he feels. The entire ordeal humanizes him, and none of it was in Tarantino’s script.

As written, Rick was never supposed to mess up his lines. Indeed the entire Lancer sequence was Tarantino’s excuse to basically make a Western inside his 60s movie, and he admits in an interview with Deadline he initially wasn’t crazy about DiCaprio’s suggestion:

“Leo said, ‘I think I need to fuck it up and forget the lines,” Tarantino said. “I just wanted to do my Lancer scene, a way to do this Western through the back door. He said, ‘I know I’m kind of fucking up your scene, but I think that would be good for the character.' I saw it as him ruining my fun, basically, but I say, ‘Fine. I’ll write a version, and we’ll do the Lancer scene straight, and with the fuck-up, knowing that in the editing room I was going to do what I wanted to.”

But as soon as they rolled cameras, Tarantino says it became clear that Rick Dalton’s fuck-up was going in the movie:

“As soon as we did that second version, the take that is in the movie, I was like, ‘OK, OK, we’re obviously doing this now.’ He was right. It was terrific and it gave the whole thing an arc that worked wonderfully.”

This then led to the creation of the scene where Rick beats himself up in his trailer. Speaking to Deadline, DiCaprio said the scene was entirely improvised but it was Tarantino who cut it all together in post-production:

“How do we create Rick’s narrative within the context of an actual set, acting on a B television show, and that led to the whole trailer moment, which was performance art. We rounded up all these subjects, and just improvised a few hours and he spliced it together in a very creative way.”

This is a shining example of how an actor can collaborate with a filmmaker to make the film or character even better than it was on the page. And for DiCaprio, the scene where Rick can’t get out his lines is the turning point for the character, as he enjoyed creating an arc for this character within the context of the Lancer sequence

“It’s this real turning point for Rick. Here he is, face to face with the new hot shit swinging dick in Hollywood television who’s got his own show that Rick used to have. And Rick can’t get his lines out. He can’t do it. What’s so amazing about Quentin is, you bring up one idea like that, and then this whole other Pandora’s Box of possibilities opens up. He makes it a Western, within a Western. He says, we have to have Rick re-preparing himself, and then walking down that Western set to do a shootout with his adversary, but the shootout is within the context of a scene…”

And after Rick’s pep talk to himself in the trailer, Tarantino says it turns Rick around:

“I said when you come back, maybe you’d been a bad actor, but now you’re going to be a slightly better bad actor who rises to the occasion,” Tarantino said. “What it meant to the movie was, it became clear that his biggest enemy is himself. He’s not facing a bunch of bad guys in a Western anymore; his bad guys are his own demons. When he does that Wild Bunch walk to the Gilded Lily on the Lancer set, he’s facing his Mexican army, which is himself.”

DiCaprio goes on to say that while Tarantino certainly wants his actors to say their lines as-written, there’s also flexibility to improvise within that. Although it’s also possible that kind of flexibility is only afforded to actors of DiCaprio and Brad Pitt’s caliber.

Whatever the case, it works incredibly well as Once Upon a Time in Hollywood is one of the best films of the year, and a major Oscar contender in a number of categories.