Continuity mistake: When Harry is in the water going after the Sword of Gryffindor he's wearing his glasses; but after Ron pulls him out of the first thing he does is reach for his glasses on the shore.
Continuity mistake: When Bellatrix looks at Harry through the gate at Malfoy Manor, her lips are a pink color. Inside the house, when she shows him to Draco, her lips are a totally different dark red shade.
Revealing mistake: When the Order members drink the polyjuice potion, Hagrid is talking to Harry but he is not visible in the mirror on the wall. (00:14:50)
Continuity mistake: In the beginning, when Minister Scrimgeour is making a speech, there are some people standing behind him. When he finishes and is being photographed, there are suddenly no people behind him.
Revealing mistake: When Harry uses the spell "Engorgio" on the fire in a jar while talking to Ron, there is a jump cut as the flame gets tall.
Other mistake: Harry pulls a knife out of Dobby's chest, but before that, we can see there's no knife.
Suggested correction: Yes there is, Dobby is holding on to it as he falls into Harry's hands. Its not totally obvious, but the CGI people definitely put it in.
Continuity mistake: The paper on which Luna's dad draws the symbol of the Deathly Hallows first has 4 large smudges, the largest being the one on top. Cut to the next shot and the largest smudge is now on the bottom, and their general appearance has changed. (01:54:00)
