Continuity mistake: When Ron is about to cast a spell to destroy Nagini the view of him pointing his wand starts out from behind him and Hermione, before the shot changes we see Hermione turn her head towards Ron. When the shot changes to face them Hermione is looking at the snake then turns her head again.
Continuity mistake: When Filch is holding Mrs. Norris the cat's eyes are not red, but in all the other films they are.
Continuity mistake: Dobby's grave at the beginning of the movie has been moved further to the right of where it is was dug by Harry at the end of the Deathly Hallows Part 1.
Continuity mistake: When Harry jumps on the dragon, his hair is wet and messed, then it changes to dry and brushed and in the next angle, for a brief moment, it's back to wet and messed.
Continuity mistake: When Voldemort and his followers return for the final battle with Hagrid carrying Harry, the remaining building structure has fires in each section. When Harry and Voldemort land there during their duel, the fires are gone.
Suggested correction: Obviously, the fire had plenty of time to die out.
Continuity mistake: After Voldemort disapparates while Snape is dying, Harry asks Hermione for a flask for Snape's tears. She pulls a vial out of her purse. However, she hadn't had a purse during the entire prior battle, then suddenly has one at this moment. Afterwards, she no longer has the purse in any other scene.