I agree that it was much better in the first two seasons before it became a sitcom, and the '50s elements were all but removed, and it became the Fonzie show. And, yeah, the Mork episode was written as a dream. Correct me if I'm wrong, though, but there is a scene at the end where the Mork character returns and talks to his leader, proving it isn't a dream. I think that scene might have been added after Mork and Mindy was picked up. Nevertheless, there is an episode where Mork returns, and there is no effort to try to make anybody think it's a dream.