Continuity mistake: When we first see Harry drawing a cake in the dirt, his hand is in the shadow created by the sofa when lightning strikes. When we see a closeup of the drawing, his hand is in the light. (00:12:50)
Continuity mistake: When the letters start flying through the letterbox they are coming in with the address facing down and the red seal facing up. When Vernon says they are going away, the letters are now addressed side up and red seal down. (00:12:15)
Continuity mistake: In the scene following Harry's sorting, Hermione has changed sides at the Gryffindor table. (00:43:00)
Continuity mistake: In Olivander's shop, the packages Harry put down when entering the shop change position between shots. (00:24:30)
Continuity mistake: When Fluffy drools on Ron, the amount of drool changes drastically. (01:51:30)
