Before watching the movie:
I don’t recall at the moment if this started as a direct remake/sequel to Fantastic Voyage, was merely inspired by it openly, or just has a similar concept, but I do know that I was first made aware of the existence of Innerspace when researching Voyage. I have dim recollections that it might be a “suggested by” treatment of the novel sequel to Voyage?
Anyway, I also just discovered it has Martin Short as the hapless fellow who doesn’t realize he’s got a tiny explorer inside him, which ramps up my interest in it. Also, the idea of cutting back to comedy sequences outside caused by what’s going on inside reminds me of Osmosis Jones, only with live action/VFX instead of cartoon animation.