A possible scene explanation if it's needed
First, I love this movie, although I haven't watched it for a couple of years. Second, I, like a lot of people, fully believe that Prot was an alien like he claimed.
Now forgive me if this has been discussed before, but there was one scene in this film that frustrated me as far as Prot being an alien or not is concerned, and that was the aloha scene at the observatory. He doesn't move, and from memory one of the others says 'see, Prot, on this planet that's what's known as the fastest draw in the west routine' to which Prot replies 'but I do not come from your planet Dr...' whoever he was.
It came across as a crummy display by Prot, but then this morning for some reason I was thinking about this scene and suddenly realised something. Correct me if I am wrong, cos I haven't seen it for a while, but doesn't Prot explain to Bridges at one point that light travel needs to be planned or scheduled because of the number of travelers out there? If this is so, then there would undoubtedly be a firm rule in place restricting unscheduled travel unless the destination is the same as the departure point, just to avoid any chance of 'collisions'. That makes sense doesn't it? Well, it explains that scene for me anyway.