I wouldn’t at all be surprised if “He’s Still Here,” Casey Affleck’s documentary (or is that mock documentary?) on eccentric actor (or is it all performance art?) Joaquin Phoenix, turns up as a special screening on opening night at the Toronto International Film Festival.

Magnolia announced that it will open the film on Sept. 10 — one day later — in the United States. A release from the distributor says the film “follows the Oscar-nominee as he announces his retirement from a successful film career in the fall of 2008 and sets off to reinvent himself as a hip hop musician. Sometimes funny, sometimes shocking, and always riveting, the film is a portrait of an artist at a crossroads. Defying expectations, it deftly explores notions of courage and creative reinvention, as well as the ramifications of a life spent in the public eye.”

Magnolia distributed Phoenix’s most recent film as an actor, James Gray’s “Two Lovers” with Gwyneth Paltrow.