Very long shot:
When I was little, I saw a old sci-fi show on TV, where a pair of astronauts were talking to some guy on a planet they'd landed on, and the guy revealed that the planet had had no atmosphere all along, and the astronauts immediately suffocated.
Dumb plot, yes, but it TERRIFIED little me for days. I thought I might suddenly discover I couldn't breathe and just die.
Anyway, I don't know much else (or even if I'm remembering it correctly) but if anyone knows the name...?