That's an interesting idea for a movie. An imaginary director.
all the actors assume there is one, but it's just an empty chair with the word 'Director' on the back. they go through months of filming, and by the end, they've successfully completed an oscar-winning movie. upon calling the non-existent director to the stage for his acceptance speech, the actors then realize they did it all by themselves. cue emotional swelling music. roll credits.