The cast of The Hangover II say that having a difficult shoot in Thailand helped to make a better movie.

Bradley Cooper, Ed Helms and Zach Galifianakis headed to Bangkok to film a sequel to The Hangover, which was filmed in Las Vegas.

Writer and director Todd Phillips said the shoot was "tough", adding: "The city was challenging. It's a beautiful city, but it's hard to roll in with a circus the size of a movie shoot and take over their streets."

But Zach said he thinks that made the film better.

"I think angst and anxiety can cause funniness to happen, especially in a movie like this because the script kinda calls for that. If you're feeling antsy in the city you're in, I think it helps," he said.

Ed added: "Fortunately, the comedy in this movie isn't goofy, clowny comedy. It's more situational, tension-based comedy. I think Bangkok actually helped us."

Watch the trailer and behind-the-scenes footage