Revealing mistake: Right at the start when Harry is on his bed and making a light under his sheet, you can see that he is actually on something like a light panel in order for this effect to happen. For one thing, when he moves around on it, it doesn't bend like a mattress does. Also, about halfway down the bed you can just see where the sheet ends and this panel begins. (00:00:50)
Continuity mistake: After Harry opens the front door for Uncle Vernon and Aunt Marge, Vernon walks into the living room and Harry follows him. Harry stops before he walks over the door step, but when it cuts you can see he has crossed over it. (00:01:55)
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: When Marge arrives, as she walks towards Petunia, there are two gold trim bars installed between the carpet edges and kitchen floor - one in the doorway and another between the kitchen counter and wall. Both disappear in the following shots. (00:02:00)
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: When Aunt Marge is round and everybody is eating, in one shot Dudley is spooning something off of his plate, yet in the following shot his spoon is up in his mouth. (00:02:25)
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 Marge and the family are eating, Mr. Dursley pours Marge some brandy. She then tells him to pour a bit more, and in one shot he is holding the brandy bottle and glass away from each other, yet in the following shot he's pouring brandy into the glass. (00:02:35)
Visible crew/equipment: At dinner, just after Harry takes the plate from Petunia and as Aunt Marge says, "A bit more," referring to the brandy Vernon pours, in the left glass door of the hutch behind Vernon, there is a nice clear reflection of a crew member lowering his white sleeved arm off screen. (00:02:40)
Continuity mistake: While everyone is in the Dursley's dining room, before and after Aunt Marge's inflation, the plates, cutlery, food, etc., on the table and kitchen counters change positions in subsequent shots, depending on the camera angle, not due to anyone touching them. (00:02:40)
Continuity mistake: The large hutch behind Vernon actually moves over to the left, closer to the lamp, during the dinner with Marge. At the start of the dinner scene, the chair beside the hutch, behind Vernon, is at least two feet away from the small table, which holds the lamp. As Marge starts to expand, the chair is right beside the table. (00:02:40 - 00:04:25)
Continuity mistake: When Uncle Vernon is pouring brandy to Aunt Marge we see Harry picking up a plate from the floor while holding two other plates in his left hand. When it cuts Harry is still holding the two plates, but something which appears as a napkin or something has appeared in his hand as well. You can see it sticking out between the plates. Whatever it is it wasn't there in the previous shot. (00:02:40)
Audio problem: When Aunt Marge asks Vernon for "a bit more" brandy the second time, her mouth doesn't move. (00:02:45)
Continuity mistake: At the dinner table when Aunt Marge says, "You wanna try a little drop of brandy?" to her dog, you see Harry carry some plates in the background. When the scene cuts, he is standing with different plates in his hand. (00:02:45)
Continuity mistake: When the Dursleys are in the dining room, the chair located near the telephone, on the kitchen counter, changes position throughout the scene. In some shots its back is right beside the phone, in others not, and then in other shots its back leans right up against the wall and in others it is positioned well away from the wall. (00:02:45)
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 Aunt Marge says "Actually, it's nothing to do with the father..." you see Aunt Petunia lift her right arm. When it cuts her arm is down. (00:03:45)
Continuity mistake: When Harry goes to the table to clean up Marge's broken glass and when he stands at the counter as Marge blows up, there is a large rug in the kitchen, under the center cart, whose edge reaches the counter stools. When Harry storms downstairs with his trunk, Petunia and Dudley stand at the kitchen doorway and the rug is gone - it would be visible if it was on floor. (Likewise, the rug was gone when Marge and Ripper arrived, but it could be presumed that the rug was laid out before their meal.) (00:03:50 - 00:06:40)
Continuity mistake: In the beginning when Aunt Marge says, "The bitch and the pup" and Harry yells at her, Mrs. Dursley turns to look at Harry. When the shot changes, Mrs. Dursley is now facing the table, away from Harry. (00:04:00)
Continuity mistake: The cart with the TV changes its position in various shots. For example, in the close-up of Marge's legs lifting off the ground and when Marge floats out the door in the exterior shot, the cart is aligned with the doorway, then at other times it is at the inner edge of the draperies or in between. (00:04:10)
Chosen answer: Fred and George used the map to aid them in their mischievous activities at Hogwarts, and probably had little interest in what their little brother was doing or who he might be with at any given time.
raywest ★