Farrell stars as Marty, a struggling screenwriter who finds inspiration for his long-stagnant thriller after becoming tangled up in his friends' criminal dealings.
Speaking to Digital Spy earlier this year, McDonagh and Farrell discussed the shooting experience as compared to In Bruges.
"It was really easy, because it was such a big story," Farrell said. "In Bruges was kind of me and Brendan the whole way through... and on this I would come in and out of the story.
"There were so many different shorelines that were interwoven, and it was just great to have a shorthand with Martin."
Farrell went on to compare Marty with his more tormented In Bruges character Ray, while McDonagh discussed the self-referential aspects of Seven Psychopaths' screenplay.
> Sam Rockwell attends 'Seven Psychopaths' premiere for Jameson Film Club
> 'Seven Psychopaths' debuts behind-the-scenes video
Seven Psychopaths is released today (December 5). Watch a trailer below:
Gallery - 'Seven Psychopaths' character posters: