Submarine
In anticipation for season 4, I rewatched all the old episodes. It is a great show!
In season 2, Bellamy is stealthing around mt. weather, and uses the phrase "it is like a submarine in here". My question is, how does he know what a submarine is?
He obviously grew up in space where the amount of ocean is very limited. We know they had a school subject called "earth skills", but would they really teach you about submarines (and what they look like on the inside) instead of more useful survival techniques, like say how to make fire or navigate with stars.
Last thing I can think off would be if any movies survived the apocalypse and went into space, then maybe he could have seen the inside of a submarine in a movie. But literally no one makes popculture references in this show, and every submarine movie would be 100+ years old, so I doubt it would have any entertainment value