Innerspace

Lt. Tuck Pendleton (Dennis Quaid) is a cocky naval aviator who volunteers for a top secret experiment in which he and the craft he is piloting will be shrunk and inserted within a lab rabbit's bloodstream. But when things go terribly awry due to an attack by a rival scientist, he ends up injected into an unwitting man on the street, a hypochondriac named Jack Putter (Martin Short). Pendleton is unaware of anything that has happened after he was miniaturized, and Putter has no idea he has been injected. Now Pendleton has to find a way to establish contact with his host, convince him that he is not hallucinating, and find a way to escape to safety while also staying ahead of the evil scientists that sabotaged the experiment in the first place. Also starring Meg Ryan as Pendleton's estranged ex-wife, and directed by Joe Dante.