"It was a lot less chaotic shooting it than viewing it," admits Farrell, while promoting the film in Toronto. "The violence was completely juxtaposed with the fun. It was surprisingly peaceful."
"I think we are taking a little poetic licence," says Rockwell. "A typical psychopath does not exude empathy and some of these characters do."
The film follows Farrell's Marty, a hard-drinking Irishman and Hollywood screenwriter as he struggles to write his new movie, Seven Psychopaths. His best friend Billy is keen to figure in the movie and helps him set up the story, attracting a number of psychopaths for him to write about. Billy runs a dog-snatching business together with his dapper buddy Hans (Walken) and when they inadvertently kidnap a Shih Tzu named Bonny that belongs to a gangster (Harrelson), the Shih Tzu hits the fan ...
Seven Psychopaths has been compared widely to Quentin Tarantino's Pulp Fiction. This is a comparison McDonagh dislikes.
"I don't see it," he insists. "The film's almost kicking against Tarantino's stuff; the anti-violent aspect is questioning the cool of film violence which in some ways is what Tarantino is about. Colin and Sam and Chris and Woody - there is a joy to their performances. I sit behind the monitor listening to them saying my words and it's very funny."
Seven Psychopaths may ultimately be broader in its scope than In Bruges, but its story, like that of In Bruges, can still be seen as one of friendship between two men.
"Colin is doing kind of what Brendon Gleeson did for him in In Bruges and I am doing what he did in In Bruges," Rockwell explains. "We are switching parts in a way. You could argue that Woody is Ralph Fiennes - obviously Charlie is that gangster archetype.
"But Hans is his own entity. There's not a character like Hans in In Bruges. He's like Obi-Wan Kenobi."
"It's an ambitious movie," says Rockwell. "It's very theatrical, it has monologues, it's dialogue-driven. So it's not your usual film."
The lowdown
What: Seven Psychopaths starring Colin Farrell, Woody Harrelson, Sam Rockwell, Christopher Walken
When: At cinemas now.