Continuity mistake: When Dudley is hit by the first button that flies off Aunt Marge, we can see a table beside him with a lamp and a picture on it. When it cuts to Dudley lying on the floor, we can see the lamp and the picture have changed position. (00:04:50)
Continuity mistake: When Fred and George give Harry the Marauder's Map, Harry opens it up and on the right is Dumbledore's study. In the close-up shot of Dumbledore's study, the map is drawn with much more elaborate detail for fun and dramatic flair and the actual words of the interlocking circles are written on the map extremely differently than the previous shot. (01:00:00)
Continuity mistake: In the first exterior shot, as the Dursleys eat dinner, both sides of the kitchen window (above the patio set) are closed. When Harry says, "Oh yeah, I've been beaten loads of times," the right side of the window is clearly open, as the window's diamond shaped pattern is only towards the left side. It's also visible when the lights flicker and the window curtain on the right blows in. In the last shot, as Marge floats away, both sides of the window are closed again. (00:03:10 - 00:05:45)
Continuity mistake: When Harry boards the Knight Bus in the exterior shot, the curtain in the small window at the stairs is pushed open towards the outside of the bus. However, in the next interior shot the curtain is pushed open towards the inside of the bus. (00:09:00)
Continuity mistake: When Sirius flies off on Buckbeak, the ground on which he takes off from is a perfectly clean stone ground with nothing on it. Yet after Sirius has flown off, Harry and Hermione run across the same ground, only now it is covered in dead leaves, grass and mud, etc. (01:59:40)
Continuity mistake: When Aunt Marge's chair starts to float up, in the close-up of her legs, her feet are at least a foot off the ground and the chair even more. However, after her necklace pops, Vernon yells, "Down boy!" at Ripper, she lets go of the table and in the next wide shot, her feet are still well under the table and the chair is still touching the floor - this shot is spliced from the earlier shot, just after Ripper first bites Vernon's foot! (00:04:50)
Continuity mistake: During the dinner scene at the Dursleys, Dudley is shown in a close-up watching a game-show where a young woman is putting on large headphones. But when the shot returns to the whole room, you can see the girl on the TV putting on the headphones all over again. (00:02:30)
Continuity mistake: When the jar is smashed in Hagrid's hut, the lid stays on the smashed jar, yet when Hermione picks up the stone which smashed the jar, there is a closeup of her hand holding the stone and you can see the lid of the jar on the table. (01:21:30)
Continuity mistake: In the first exterior shot looking through the Dursley's patio doors, as they have dinner, and later when Vernon runs after Marge, the threshold is wide, flat and all white. Below the glass on the doors the trim is narrow and at the very bottom it is wide. There is a keyhole opening (on the left door) under a particular style door handle and there is a wide double lip going round the entire edge of the left door. When Petunia runs out, the threshold is higher up and mostly brick, with a thin strip of white in the middle. The style of the patio doors under the glass is completely different, there is no keyhole, the handle style differs and there is no double lip on the door. Additionally, the large clay pots with plants, beside the doors, change from being glazed and shiney to being unglazed, its plants differ and things change position. (00:02:00 - 00:05:00)
Continuity mistake: As Harry approaches Lupin's desk, the open trunk is visible to his left, near the window. When Lupin tucks his belongings away in his trunk, items such as the books are positioned differently. (02:06:30)
Continuity mistake: As Harry reaches Lupin's office, Lupin stands by the bookcase and the front end of the valise under the desk points towards the right. However, when Lupin says, "No, no, I resigned," the front end points the opposite way. Then when Harry walks to the doorway, it's the same way as the first shot. (02:06:10)
Continuity mistake: After Ron, Hermione and Harry run out of Hagrid's they hide behind the pumpkins, while the other Hermione and Harry look on as they hide behind trees. When Hermione comments about her hair, the tree branch she moves away is completely different between the shots facing her and the shots facing Hagrid's. (01:52:10)
Continuity mistake: When Harry gets on the Knight Bus, as he's stepping on, half of his jacket is wet (on the bottom) from falling on the wet pavement. Once he's on the bus, there's a quick shot of him from the back, and it is all dry. (00:08:40)
Continuity mistake: In the first shot at dinner, when Marge says, "Finish that off for Mommy...Rippy-pooh." she places her plate down on the carpet for Ripper. In the view under the table, Harry's and Vernon's legs are visible and Vernon walks past Dudley. In the next shot, Vernon comes from the side and walks past again. (00:02:25)
Continuity mistake: The cuts including the one with butterfly closures on Hermione's cheek and the scratches on Harry's cheek change position/characteristics in many shots throughout, even in consecutive shots.
Continuity mistake: After leaving the Dursleys, Harry sits down on the pavement beside his trunk, with no room between the two. When he turns to look at the squeaking swings, in the shot from behind him, there is at least a foot of space between Harry and the trunk. Yet in the next shot that faces him, the trunk is beside him once again. (00:07:20)
Continuity mistake: When Vernon holds Marge's hands as she floats up, in the shot just before she yells, "Don't you dare!" Dudley stands behind Petunia with the napkin hanging from his collar. After she floats away screaming, in the close-up of Dudley the napkin stains differ and it now has a glob of white cream which he promptly wipes off and eats. (00:05:40)
Continuity mistake: As Marge is inflating, there is a close-up of her knees, as the skirt rises revealing the garters. In this close-up her cloth napkin is on the table right in front of her, though in the previous and following shots it is on the floor. (00:04:45)
Continuity mistake: While Hermione tries to coax Beaky to follow her and Harry, in the wide shot she and Harry stop, she tosses the ferret and throws her hands up in the air. In the next two close-ups their positions differ. (01:54:05)
Continuity mistake: After bowing to Buckbeak, Harry removes the chain from the ring on the wood post, with the crow sitting on it. In the close-up, the wood post with its metal hardware, and the actual black crow, all noticeably differ from the previous and following shots.
Answer: This didn't happen in the book. It appears to be done purely for comic effect in the movie, showing Dumbledore's eccentric and quirky nature. He's seemingly oblivious to what he's doing and how it affects Ron.
raywest ★