Leonardo DiCaprio, Brad Pitt and the cast of Once Upon A Time…In Hollywood attended a special screening of the film with Q&A in Los Angeles on Nov. 21.

After a showing of Once Upon a Time in Hollywood at the DGA Theater, in Hollywood on November 21, a ton of the film’s talent—actors Leonardo DiCaprio, Brad Pitt, Bruce Dern, Julia Butters, Timothy Olyphant, Dakota Fanning, Emile Hirsch, Mike Moh and Margaret Qualley, as well as casting director Victoria Thomas and actor-stunt coordinator Zoe Bell—chatted about the movie in front of a packed crowd.

As you’d expect from his previous work, Leonardo DiCaprio put in a lot of work into his portrayal of Dalton.  For instance, the nervous stammering Dalton sometimes drops into was inspired by a friend of DiCaprio’s who “has a nervous energy around what his future may hold.” And, as the film depicts, Dalton is on the verge of becoming a severe alcoholic.

“This whole idea is he is an actor who had his big shot in television and does he have what it takes to make that transition to this era of director-driven films,” DiCaprio explains. “Is he going to transcend his own insecurity and self doubt to make it or will he just be happy to accept the fact he loves being an actor? And that’s what Julie’s character sort of symbolizes. ‘Hey man, you’re working. Life is good.’ He’s so consistent in feeling sorry for himself. All that charater stuff just wove itself into what Rick was with conversations with Quentin.”

When asked how often improvisation occurred on set, DiCaprio said: “I would say I don’t know if it’s uncommon. [Tarantino] definitely gives you rein to improvise but in a lot of ways his words are Shakespearean. You take his lines very seriously. You want to give him the goods. But when he lets you go off and do your own thing, that’s a lot of fun too.” Such was the case in the scene where DiCaprio’s character melts down after flubbing lines: “That was great. Quentin gave me a lot of bullet points of thoughts that I could do and improvise. It was all in the trailer with [cinematographer] Bob Richardson, and I got to smash the hell out of that trailer. A lot of fun.”

Leonardo DiCaprio also Praised Brad Pitt’s ‘Subtle’ Performance: “Brad and I had some sequences together but seeing this sort of amazing portrayal..what Brad did is really not easy to do,” DiCaprio says. “You have to go back to Alain Delon or Steve McQueen. That kind of subtle power. It was so striking when I first saw it.”