Other mistake: In chapter 30 of the American hardcover edition, Harry and Hermione find seats in the topmost row at the Quidditch match, but when Hagrid comes to tell them about Grawp he squeezes his way through the row behind them. If Harry and Hermione are in the topmost row, there cannot be a row behind them. (Corrected in later Editions).
Question: When Harry is brought to Dumbledore's office after dreaming about Mr. Weasley being attacked, what does Dumbledore mean with "but in essence divided"?
Question: During the Occlumency lessons, when Snape sees the memory of Aunt Marge's dog attacking Harry, why does he want to know whose dog it was?