LAS VEGAS—It’s rare that a filmmaker will take a moment out from talking about his movie for a word about his sponsors. However, that’s what The Hangover director Todd Phillips does in the middle of an interview at Caesars Palace. He says he still can’t get over the fact that his little movie about a group of guys who have a night in Vegas so memorable they can’t remember a thing has become one of the most promoted movies of the summer. It’s from Warner Bros., a studio that was also gearing up for summer releases of Terminator Salvation and Harry Potter and the Half-Blood Prince.

“After we finished the rewrite of the script and got it to where we wanted it to be, the studio said, ”˜If you want to make it R-rated, you have to make it for this number,’ and they wrote a number down and slid it across the table,” Phillips says. “They said, ”˜If you can make it for that number, we will see you at the first test screening.’ That meant we could cast whomever we wanted and shoot wherever we wanted. We said, ”˜Great,’ and we went and made the movie. Everyone thinks Warner Bros. is this huge empire of filmmaking, but I think that in the last two years they have been making some of the edgiest studio stuff, movies like Watchmen and Observe and Report, and even The Dark Knight. They believe in filmmakers. The fact they showed this film at [the film trade show] ShoWest next to Terminator and Harry Potter was a great vote of confidence.”

Phillips took his casting freedom seriously. He put four relatively unknown actors (Bradley Cooper, Zach Galifianakis, Ed Helms, and Justin Bartha) in the lead roles and gave his best-known cast member, Heather Graham, the smaller role of the hooker with the proverbial heart of gold. Graham says that although Phillips may credit his casting freedom to the studio, his résumé shows that he’s done this before.

“If you are going to make a movie, you have to choose from a list of the top people, and most of those people are already working, so you might not be able to make the movie,” Graham says. “So he takes new people and gives them a shot. Will Ferrell was not a movie star until he did [the Phillips-directed comedy] Old School, so he [Phillips] kind of jump-started his career. I remember running into Will when I was about to do this movie, and he said, ”˜He hired me when no one would hire me, and that is pretty amazing.’ He has faith in himself. He feels he doesn’t have to hire Owen Wilson or Ben Stiller. Instead, he will think, ”˜I am going to hire these new guys,’ and it turns out to be amazing.”

Although TV’s CSI: Crime Scene Investigation has been shot in Las Vegas since it went on the air in 2000, it’s rare for films to spend much time in the suburbs of Sin City. Or go outdoors during the daytime. Phillips says he knew that if he was making a movie about a group of men who were trying to find out what had happened to them the night before, there would be a lot of daytime shots and several scenes that would take them outside the city.

“I liked that you see Vegas in the daytime, which you never really see because it is not particularly nice-looking. Vegas at night is all lights, and when you see it in the day it’s like waking up, and you think, ”˜This is not how it looked last night.’ I think it looks great in the movie, but there are things you never see in movies. Even taking the camera up to the roof [of Caesars Palace] and looking out at the city gives you a dingier feeling.”

The Internet Movie Database has confirmed that a Hangover sequel is already in the works. That’s highly unusual, given that the studio has no idea if the movie will make any money. Phillips admits that he was thrilled to be told he could start work on a follow-up script, but he says it’s unlikely to happen if the movie doesn’t perform well at the box office.

“I don’t want to get into it, because it always sounds lame to talk about these things. Things might change and people then think the studio changed it, so it’s safer not to talk about it. That’s not because I am trying to be protective of it. The studio is supportive of the idea, but the movie has to do well. But we are tossing around some [script] ideas.”