The alumni cast of a space opera television series have to play their roles as the real thing when an alien race needs their help. However, they also have to defend both Earth and the alien race from a reptilian warlord.
"One of my favorite moments in "Galaxy Quest" takes place as a Red Digital Readout is ticking off the second until a spaceship is blown to smithereens. The only person who can save it is a teenage science fiction fan far away on Earth--and he has just been ordered by his mother to take out the garbage. But then the ship is saved! How? I won't spoil the moment, except to say the ship is modeled in every possible respect on a ship that appears on a TV show, and that includes a digital readout that is also consistent with TV cliches." - Roger Ebert