Very tough sci-fi movie question!?

I saw this film several years back (90's?) but completely forgot the name of it. The back story is a man and a robot are living and working on a spaceship, but the bulk of the film involves watching them sitting in a cinema on their spaceship as they comment on a sci-fi movie they are watching from the 50/60's. In fact, most of the film is over the back of their heads! I know this is a tough one but I'd really appreciate the help!