Continuity mistake: When Xenophilius draws the Deathly Hallows symbol, he draws it so that the bottom of the line touches the bottom of the circle. The shot cuts away and back again when he draws the triangle, but the line is no longer touching the bottom of the circle. (01:49:40)
Revealing mistake: Throughout almost the whole movie Harry's glasses don't have lenses in them. Only in two or so scenes do they appear.
Continuity mistake: In the second to last shot, where Lord Voldemort is drawing the Elder Wand out of Dumbledore's hands, and then thrusts the wand into the air, Lord Voldemort's arm has hair on it. In the book, he is described as completely hairless, and in every other shot in every other movie, they have been careful to remain true to this.
Continuity mistake: When Hermione is being tortured by Bellatrix in Malfoy Manor, we see a closeup of Hermione crying, and then Bellatrix reaching over to Hermione's right arm to carve "Mudblood" into it. But in the next shot, we see Bellatrix carving it into Hermione's left arm instead. (01:59:40)
Continuity mistake: When Xenophilius Lovegood is drawing the triangle in the Deathly Hallows symbol, he starts with the left side, moving the pen down on the page. The shot changes to Harry, Ron, and Hermione, but we can still hear him drawing and the sound indicates that he never lifts his pen from the paper. However, when it cuts back to him finishing the symbol, the right side is already drawn and he is finishing the bottom. With the way he was drawing it, he should have drawn the left side first, then the bottom, and finally the right. However, this would not be possible to do unless he lifted his pen from the paper, which, as stated before, the sound indicates that he did not do. (01:49:50)
Continuity mistake: In the forest, when Hermione is sitting with her back against a tree, reading, the book changes position between shots after Harry walks over to her. In a close-up, the top of the book is over her knees, in the following wide-shot, the book is below her knees, and then moves back to its original position in the next shot. (01:33:10)
Factual error: During the scene when Harry and Hagrid are on the motorbike going through a tunnel, the bus signals that it is going to Dartford. Both of the tunnels at Dartford carry north-bound traffic, going away from Dartford - all south-bound traffic, towards Dartford, travels on the bridge (visible in some shots). No traffic enters the tunnels heading south-bound towards Dartford.
Continuity mistake: As the Death Eaters disrupt Bill and Fleur's wedding, Ron holds Hermione's right hand and Harry holds her left hand as she disapparates with them in tow. However, when they apparate onto Shaftesbury Avenue, Ron and Harry's positions have switched, now Harry holds Hermione's right hand and Ron holds her left hand. (00:36:05)
Continuity mistake: At the Ministry of Magic, as Yaxley is reprimanding Ron, who is disguised as Reg Cattermole, the initial on Yaxley's Ministry tie pin changes direction. In one shot, the letter "M" is tilted to the left, and in a subsequent shot, it's slanted in the opposite direction.
Continuity mistake: When Harry, Hermione, and Ron confront Mundungus about the missing locket, Mundungus knocks over a tall stack of Daily Prophets on the floor. However, when Mundungus puts the Daily Prophet (with Umbridge on the front page) on the table, the stack is back upright behind Hermione.
Continuity mistake: Early in the scene where Hermione is cutting Harry's hair in the tent, Ron is lying on the bed with his arm in a sling and wearing what looks like a sweatshirt. In the shot where he comes in and says, "The sword was stolen," he is in a different outfit and his sling is gone. Since we could heard the scissors cutting Harry's hair at the beginning of the shot, we know that Ron was wearing something different and was in a sling just a moment before he walks in.
Continuity mistake: Near the end, when Hermione jinxes Harry's face to disguise him, she removes his trademark glasses to hide his identity and shoves them into her own pocket. Harry is still without his glasses during the confrontation at Malfoy Manor where his identity remains in doubt (his glasses would give him away). However, as Wormtail (Pettigrew) is taking both Ron and Harry to the cellar, Harry's glasses are suddenly back on his face, even though Hermione was separated from the group.
Continuity mistake: When Mundungus is confronted about the locket, as he says, "Could I help it if Mad-Eye fell off his broom," Ron places his hand on the chair with his hand facing away from Mundungus. Depending on the angle of the following shots, Ron's hand is either facing Mundungus or facing the opposite way.