Affleck makes his directorial debut with the film, which follows his actor brother-in-law Phoenix's attempt to reinvent himself by launching a hip-hop career.
Several critics have suggested the movie is an elaborate hoax but, speaking at the movie's premiere at the Venice Film Festival in Italy on Monday (06Sep10), Affleck admitted he wants viewers to be confused.
He told reporters, "Elliptically, I would say... I sincerely don't want to influence people's interpretation. I can tell you there is no hoax. It makes me think of Candid Camera or something...
"I'm very interested to hear those sorts of reactions and I appreciate that point of view, and I understand how a lot of this movie could be confusing in terms of, 'Oh well, it seems like something's real or not real.'"
But Affleck caused further confusion when he revealed that rapper Sean 'Diddy' Combs' cameo role in the project was "an act".
He explained, "The role that (Combs) played in Joaquin's life was to be the bearer of bad news. He was the hammer that crushed the dream. All of that is a little bit of an act."