In the scene where the crew is going down in the shuttle, Guy worries he is going to get killed and asks everyone what his last name is, nobody knows. Later, on the planet, Jason (Tim Allen's character) calls him Fleegman, which we found out in the end was his last name.
Without having reviewed the movie, I believe this can be explained. Fleegman would have been his "real-life name", whereas his comment referred to the fact that his character in the Galaxy Quest TV series had no last name. Any other opinions on this?
The scene in which Guy freaks in the shuttle was written longer into the script, in which while he's ranting about his name he declares that it's Fleegman. However the script was never changed after this was removed...
OK, this one really bothers me also. It is also ironic that Captain Taggart called him Fleegman right after Guy had just mentioned that no one knew his last name. I suppose this is in reference to the scene which was cut when Guy actually told his last name. I guess what I am trying to say is why do they cut out IMPORTANT scenes in movies?!!?! Those are the worst slip-ups of all!
That could be a goof, but I always thought it was intentional. When Guy thought he was a fodder character to be killed off, he didn't have a last name because he wasn't important enough for one, like he said. By the end of the movie however, he suddenly gains a last name because he is important and really one of the leads. I could be reading into it too much of course, but that was the immediate impression I got.