This was recommended to me by my friend Hollie five or six years ago. I finally got around to it!
A test pilot (Dennis Quaid) is miniaturized in a top secret experiment but an attack on the lab sees him injected into the body of a hypochondriac (Martin Short) instead of a rabbit. Now he has to guide his unwitting host to avoid corporate espionage, attempted murder, and falling in love with the pilot's ex-girlfriend (Meg Ryan).
Short does most of the work in this film. Basically, Quaid sat on set and talked into a mike for almost all of his screentime. Also, his character kind of sucks. We're supposed to root for him to get the girl in the end but he's an alcoholic with a death wish and that really doesn't change by the time the credits roll. It would be much more compelling if the romance were between the two men but in 1987 that was probably a bridge too far.
Innerspace was directed by Joe Dante. In a hilarious bit of coincidence, I found out the Movie Club picks for this weekend include Gremlins, also directed by Joe Dante. And, one of the people I visited with over Thanksgiving has never seen Gremlins. So now I have to force *ahem* introduce her to this most magical Christmas classic.
Fantastic Voyage is the better "shrunk inside a human body" movie but it's not currently streaming except for rent. Innerspace is a fun, mostly kid-friendly watch that is streaming for free on Kanopy.