Continuity mistake: In the cemetery, the gash on Harry's left cheek changes depending on camera angle, such as during Priori Incantatem when Cedric says, "Take my body back..." and then when Lily says, "Sweetheart, let go..." (02:04:30)
Continuity mistake: In the Great Hall, after Hermione quips, "Well spotted!" Ron imitates his brother (when he asked Angelina to the Yule Ball) by lifting up his arms to mimic dancing, and Snape promptly smacks the back of Ron's head. In the next shot, Ron holds a pencil in his formerly empty right hand. (01:11:15)
Continuity mistake: Towards the end of the Yule Ball, when Ron and Hermione walk to the staircase, seated on the stairs are two girls who are comforting a third girl in the center. When Hermione shouts, "Ron you spoiled everything," the girls' positions change between shots. (01:18:20)
Continuity mistake: After Fred and George drink the aging potion, when the twins jump over Dumbledore's Age Line, in this overhead shot Hermione sits at the edge of the long bench, with the closed book and crossed legs. Yet, in the next shot, as Fred and George begin congratulating each other, Hermione sits a few feet away from the edge, still with the closed book and crossed legs. (This is before she moves her seat and opens her book.) (00:29:00)
Continuity mistake: In the DADA class, whenever there is a shot facing the class room, we can see that Ron and Harry are in the middle of the class room and Parvati and Padma are on the viewer's right side of the room (screen). Yet, when Moody makes the spider float from Padma onto Ron's face, in the shot facing Ron, the spider floats onto his face from the viewer's left side of the room (screen) whereas it should have been the right side of the room (screen).
Continuity mistake: In class, when Moody shouts, "And hear across classrooms!" he throws the chalk at Seamus, and the way Seamus ducks over his desk noticeably differs between the two shots; he first leans down on his right arm, then on his left. (00:23:10)
Continuity mistake: At the Quidditch World Cup, when the kids reach the top, in the first shot facing them their positions are Cedric, Ron, Fred/George and Ginny. Just before the shot cuts, Ginny is just about to move behind a twin, and more to the point, three members of the Irish zoom by on their brooms between Ron and Cedric. In the next shot (from behind), as the Irish are still zooming by, now their positions are Fred/George, Ron and Ginny, with the Irish zooming by between Ron and Ginny. Between shots, Ginny has moved past three people and the zooming Irish on their brooms. Don't confuse the hat wearing twin for Ginny; her hat is green with a black buckle band and the twin's hat is green stripe. (Clearer on fullscreen DVD.)
Continuity mistake: After Harry overhears Snape and Karkaroff, when Snape confronts Harry and mentions the Gillyweed, the shelves behind the ladder in the store room are quite visible. Once Snape finds the bottle of Veritaserum things behind the ladder differ.
Revealing mistake: At the first challenge, just before the Horntail makes its appearance, there is a tight close-up of the egg as Harry stands in the stone "doorway" in the background, on the left. Clearly it is not Daniel Radcliffe, but his stand-in (his face differs and he has a shorter, bowl-type haircut) who is standing there, for this one specific shot.
Suggested correction: I watched this scene more than once and I never noticed any stand-in. I would need a picture to prove it. Besides, why would they need a stand-in in this scene?
Continuity mistake: When Harry is attacked by a multitude of Grindylows he sustains numerous injuries, particularly the one on his jaw and neck. The position and characteristics of that wound repeatedly change in the following shots.
Continuity mistake: When Hagrid stabs Professor Flitwick in the hand with his fork, the fork changes places slightly between the wide shot of them and the close-up of Flitwick's hand, even though the fork hadn't been removed yet.
Continuity mistake: When Harry takes a bath in the Prefects' bathroom, the robe behind him repeatedly changes position throughout the scene. (01:23:20)
Continuity mistake: When Harry's name has just come out of the Goblet, we see a shot of Hermione with Ron in the background. In this shot, Ron is looking up at Hermione. A second later from a different angle, Ron is looking down, then moves his head to glare in Harry's direction. Nobody can move that fast. (00:32:45)
Continuity mistake: When Harry is on the Hogwarts Express, it is apparent that his scar is missing or very much out of place. Then during the second task, when Harry is swimming, the same thing happens.
Continuity mistake: During breakfast in the Great Hall, after Harry dribbles on himself, he and Ron are seated right beside one another and likewise their plates. When Nigel brings the box, all of a sudden there is a huge gap between them and a convenient open space on the table to place the box. (01:05:05)
Continuity mistake: When the Horntail is out for Harry's blood, in the overhead shot, as he hangs on the window frame his sleeve is pulled up showing his bare arm. However, in the next close-up as he still grips the frame, his sleeve is tucked tightly into his glove. (01:00:50)
Continuity mistake: When Ron glares at Harry in the Great Hall, he is angry with him for getting his name into the Goblet, but his face has dramatically changed from the previous shot (where he is in the background, behind Hermione).
Continuity mistake: When Hermione is walking over to wake up Ron she places a candle on the table. When it cuts the candle has moved closer to the edge of the table.
Continuity mistake: Right before the third task, Igor Karkaroff puts his hands on Krum's shoulders. In the next shot, however, his hands are off his shoulders and he is standing a respectable distance away. This change continues throughout the rest of the scene.
Continuity mistake: At the Yule Ball, when Harry, Ron, Padma, Parvati, and eventually Hermione, are sitting at the table, Ron's awful dress robe is lying on the table behind him, and it changes position between shots. (01:17:00)