It's a genuinely amusing and worthwhile comedy that should be rediscovered. This is precisely the kind of movie you can enjoy with everyone—kids won’t encounter anything unsuitable, nor will older relatives feel uncomfortable. It hails from the 80s, so it shows its age, but I appreciate older films, personally. The plot is quite strong and centers on an experiment gone awry involving shrinking a ship with a person inside, intended for introduction into a lab rabbit. When thieves target the laboratory to steal this technology, one of the scientists flees and accidentally injects the shrinking liquid into an unsuspecting individual. The events that follow are genuinely funny. Dennis Quaid delivers an adequate performance as the pilot of the ship, a brave fighter who volunteered for the experiment. I felt he stayed within his usual style; it wasn't a particularly challenging role, mostly involving him showing off. Martin Short was much better, portraying a timid man who unexpectedly found himself caught up in this situation after being injected unwillingly. He brought an interesting development to the character, as he gradually gains confidence and a sense of adventure. Meg Ryan is given very little to work with; her role seems primarily about looking attractive and appearing frightened. Joe Dante deserves recognition for his contribution to this film. I’m not overly familiar with his other works, but I believe this fits well with his typical style. The movie isn't exactly scientifically accurate (I doubt the scientific community has ever considered anything like shrinking objects or people), but it compensates with humor and a lighthearted, good-natured feel. The special effects team did impressive work, both in depicting the ship’s miniaturization and in the scenes set inside the human body, where they achieved a convincing level of realism.

Source on TMDB