Continuity mistake: During the scene where Snape confronts Harry roaming the hallways at night with the Marauder's Map, the position of the pull strings hanging down from Harry's sweatshirt hood changes several times between shots. At first the strings are tangled together, but during later shots the strings are hanging down apart, then back to being tangled, then apart again. This happens once more when Prof. Lupin and Harry are talking immediately afterwards in the Dark Arts classroom. (01:13:05)