Watching the John Carpenter film "Dark Star" which has some interesting ideas, but such a low budget, it is tough going at times. I was thinking about what the top sci-fi-coms would be. I don't think this film would make the top ten.
So here is a the beginning of a list:
1) Dr. Stangelove - I think it qualifies for sci-fi because of the Doomsday device and this film is very funny, particularly the performance of Peter Sellers, but I also love George C. Scott and Slim Pickens.
2) Back to the Future - One of the best time travel scripts, it almost makes sense.
3) Galaxy Quest - The best Star Trek film after Wrath of Khan.
4) Buckeroo Banzai - If you don't get it... That's your problem.
5) Ghost Busters - Is this a horror comedy? A fantasy comedy? I'm counting it because of the gear they have "Don't Cross the Beams".
I'll have to figure out the other five later.