Revealing mistake: As Kevin is flying off the front porch on the toboggan, you can see the small wheels mounted on the bottom of the sled to aid in its "jump". (00:25:30)
Revealing mistake: In the final game against Iceland scene, there is a point where you can see that the people in the stands are actually cardboard cut-outs.
Revealing mistake: In the Forbidden Forest, HRH are introduced to Grawp. Just as the giant lifts Hermione off the ground, in the shot from behind her, Hermione's legs disappear below her calves; the digital lines are actually visible. Slow-mo is not necessary. (Only visible on fullscreen DVD.) (01:29:40)Super Grover
Revealing mistake: When Troy says "I'll sing with her," Ms. Darbus turns around "in response" to his voice before he even says anything.
Revealing mistake: When Hallie trashes Annie's cabin and the huge water balloon is about to fall on Annie's head, the camera is at a downward view and Annie clearly steps into the trail of the balloon instead of jumping away. (00:18:05)
Revealing mistake: Just after Harry attacks Snape at the Shrieking Shack, he insists on knowing about Peter Pettigrew. In the next shot, as Lupin says, "He was at school with us. We thought he was our friend," there are wedges under the wheels of the piano, however, in the following shots they're gone. (01:34:10)Super Grover
Revealing mistake: After Carmen rescues Juni, as they fly over the city she says, "Hang on butterfingers." In the following close-ups, where is the handcuff with the broken chain on Juni's wrist? He is not wearing it on either wrist in any of these close-ups. It's obviously back in the following shots. (00:41:45)Super Grover
Revealing mistake: In the part in the motel where THING is doing morse code on the table to Gomez you can see the cut-out in the table where the guy's hand is sticking through the table.
Revealing mistake: Aboard the Hogwarts Express, when Harry stands beside the open window and sends Hedwig off with the letter for Sirius, surely his hair and clothes would be wildly moving about, because of the strong wind from the fast moving train.