Harry Potter and the Philosopher's Stone/Harry Potter and the Sorcerer's Stone - Incorrect Chess Setup
With all the chess talk elsewhere, I can't believe people missed this. Page 205, when they take the places of 3 chess pieces, Ron says: "Well, Harry, you take the place of that bishop and Hermione, you go next to him instead of that castle." In initial chess setup, the bishop is not next to the castle; the knight (which Ron becomes)is in between them. The rest of the discussion indicates that the pieces are indeed in their initial positions ("White always plays first...").