15 Things In Harry Potter That Don't Make Sense

9. What Was Snape's Contribution To Guarding The Philosopher's Stone?

During the Philosopher's Stone, Hogwarts acted not only as a school for young witches and wizards, it was a safehouse for the storage and protection of the titular artefact. Taken very seriously, given the nature of the stone, it was kept behind a gauntlet of traps to keep anyone from getting to it.

First, any intruder would have to get past Hagrid's giant three-headed dog, Fluffy, before Professor Sprout's Devil's Snare trap, Professor Flitwick's flying keys, and Professor McGonagall's game of wizard's chess. In the books there is a fifth, potion-based trial set by Snape, but this is absent from the movies.

On the face of it this doesn't seem like that big a change that would have too much impact on the movie, and it wouldn't have been if not for the fact that Professor McGonagall explicitly told Harry, Ron, and Hermione that Snape was one of the professors helping to guard the stone. If that is the case, then what exactly was he doing to help? Since his trap in the books did not make the cut in the movies, it would appear nothing.