Since "mockumentary" director Casey Affleck already admitted that his Joaquin Phoenix film I'm Still Here is a hoax, he's now moved on to other revealing tidbits about making the so-called doc...

Last night on Leno, Affleck said the following: "The movie comes out, the critics liked to say, 'This is crazy, this is disturbing, this is sick and we should be worried about him,’ but while it was happening, people were happy just to mock him."

He goes on to admit that no one ever talked to him, worried about Phoenix's erratic behavior. Kinda sad, huh? Even the none of it was real!