The Keeper of the Keys

• Continuity Error: Hagrid tells Harry that James an Lily were Head Boy and Head Girl when they were at Hogwarts.  However, later in the series, we learn from Sirius that he and James were never Prefects, that Lupin was the only one to get the badge.  A student cannot become Head Boy unless he has been a Prefect.

•  Possible Continuity Error:  I always wonder why Hagrid is allowed to do Magic in front of the Dursley's when Harry is not.  He's not alone, either.  Mr. Weasley performs magic in front of them, and so does Dumbledore for that matter.  However, when Harry casts a patronus in the fifth book, he's not just in trouble for using magic while still underage, he's also in trouble for doing magic in front of a Muggle.  Yet no one says anything to anyone else when they do it.