Can anyone tell me the name of this movie?

Question

It's an old movie 70's or 80's I think.

It's about people that go to a space convention and think it's the real thing... thats all I know

Answer 1

wow i definitely was gonna say Galaxy Quest. But someone beat me to it xD

Answer 2

Galaxy Quest

Answer 3

Could you possibly be thinking of Galaxy Quest from the 90's starring Tim Allen and Sigourney Weaver?

http://www.imdb.com/title/tt0177789/

In the movie, they are the stars of a "Star Trek" like tv show who, along with the rest of the show's "crew" are making an appearance at a sci-fi convention when real aliens from outer space, who have been watching the show for years via signals that have travelled into outer space, ask them for help to defeat their enemy. The aliens are under the impression that the tv show was real, and believe that Tim Allen and the others could help them.

It's a really cute movie.