Naive aliens kidnap their favorite heroes to fight a deadly foe, without realizing said heroes are really actors from a canceled TV show, which they have misunderstood as documentaries.
The best sci-fi comedy, cleverly parodying its source material while still maintaining an affection for it. One could aptly characterize it as Spinal Tap meets Star Trek. Plus the story itself is exciting and the characters well-realized. The entire cast is excellent, but Rockwell's paranoid redshirt steals the film.
By Grabthar's Hammer, watch this film!