Revealing mistake: In the scene at the beginning of the movie where all of the letters from Hogwarts are coming into the Dursley's house, it causes everything to shake. It is quite obvious, however, that it is just the cameras that are moving as no objects in the room are moving at all (ie. the curtains, or any of the knicknacks). (00:11:30)
Audio problem: Amidst the flying letters, as Vernon begins to chase Harry, when he yells, "Give me that!" and continues with, "Give me that letter!" his lips do not move when visible on screen. (00:11:40)
Audio problem: During the scene with the "flying" letters Harry gets one letter and tries to go in his "room", but Uncle Vernon grabs him. When Harry yells "They're my letters," not only his mouth doesn't move but his voice sounds much deeper than in the rest of the movie (it sounds more like his voice in Chamber of Secrets). This indicates that this line was overdubbed long after the main filming, when Daniel Radcliffe's voice has already begun to change. (00:11:55)
Revealing mistake: When the letters burst through the letter opening, which has been covered by a piece of wood, you can see that the piece of wood was pre-cut. (00:12:00)
Revealing mistake: The wooden board is already broken before the mail comes flying through the mail slot. (00:12:00)
Continuity mistake: When the letters start flying through the letterbox they are coming in with the address facing down and the red seal facing up. When Vernon says they are going away, the letters are now addressed side up and red seal down. (00:12:15)
Continuity mistake: When Dudley sits up when Hagrid knocks on the door, he is sat up. Camera cuts and he is sitting up again. (00:12:20)
Visible crew/equipment: In the opening shot at the hut on the rock, when the camera pans down to Harry lying on the floor the long marks that are taped to the floor near the couch are visible. These are the positions of Vernon and Petunia when confronting Hagrid about Hogwarts. (Visible on DVD fullscreen.) (00:12:25 - 00:16:30)
Continuity mistake: At the hut on the rock, after the camera pans sleeping Vernon and Petunia, there's an overhead shot of Harry and Dudley downstairs. In this shot the hanging light, its switch and cable are visible over the stairs. Note, the cable switch hangs down low, parallel to the droplight. However, when Vernon and Petunia are at the stairs, and she turns on the light, the cable and switch are now perpendicular to the droplight, raised higher up parallel to the wood above. Seen in following shots as well. (00:12:25)
Continuity mistake: At the hut on the rock, after Harry draws the candles in the dirt, he glances behind him at Dudley's watch. In the next close-up of the watch, as it turns 12:00, the watch is actually on Dudley's wrist (notice his fingers) the opposite way from the previous shot. Note the distinctive design around the watch face. (00:12:35)
Continuity mistake: While Harry lies on the floor at the hut on the rock, with his finger he draws birthday candles atop the birthday cake. When Dudley's watch hits 12:00, in the next shot of Harry, the candles visible on the floor do not resemble the ones in the previous and following shots. (00:12:35)
Continuity mistake: When we first see Harry drawing a cake in the dirt, his hand is in the shadow created by the sofa when lightning strikes. When we see a closeup of the drawing, his hand is in the light. (00:12:50)
Continuity mistake: At the hut on the rock, Harry lies on a grey blanket spread on the ground between the fireplace and the couch. When Hagrid bangs on the door, Harry quickly jumps up and hides, leaving the blanket behind. Though the blanket is visible on the ground, in some shots, it is however, gone in the three wide shots with the Hagrid body double, as he zaps a tail on Dudley, then as all the Dursleys run upstairs, as well as the shot after Hagrid says, "We're a bit behind schedule, best be off." (00:12:55)
Continuity mistake: When Hagrid knocks down the door of the hut on the rock, in the close-up of the bottom door bolt and the piece of moulding, the bolt is clear of the latch on the moulding as they both fall. Yet, in the wide shot the bottom bolt is still within the latch on the moulding, as they both fall. (00:13:05)
Revealing mistake: At the hut, when Hagrid bends Vernon's gun, if you look closely, you can see that there is a mark on the gun. When Hagrid bends the gun, the bend is exactly where the mark is. This is most visible on the DVD. (00:13:35)
Suggested correction: This is not a mark. It is either a scratch or a small piece of dirt on the shotgun. No mistake here.
Factual error: When Hagrid visits the Dursley family in the hut on the rock, Hagrid grabs and bends the shotgun barrel while it is still being held by Mr. Dursley. This is impossible. The gun is made of strong metal, and when Hagrid grabs it, it starts bending, while still in Dursley's grip. Seeing as how Hagrid (the half Giant) is very strong, he should either knock Dursley to the floor or pull the gun straight out of his hands (and maybe his arms with it), if Dursley were to really keep hold of the gun as it is bending. Mr. Dursley must have one strong grip. (00:13:35)
Revealing mistake: After Hagrid says, "Dry up, Dursley, you great prune," in the next shot just as Vernon fires the bent gun, before the hole actually appears, the light at the muzzle end illuminates the floor above and the outline of the pre-made hole is visible. (00:13:35)
Visible crew/equipment: Hagrid surprises Harry with the box of birthday cake and Harry opens the box. In the close-up of the cake, as Harry holds the box with his left hand and moves the blue string with his right hand, a crew member's finger is visible under the box, over Harry's left shoulder. Obviously it is someone holding the box underneath, while Harry holds it with one hand. (00:14:10)
Visible crew/equipment: When Hagrid enters the hut on the rock, as well as when he leaves, the bare floor near the front door is clearly visible. However, when he says, "It's not everyday your young man turns eleven, now is it?" in the next shot as Hagrid sits down, on the floor to his left is the crew's mat with marks for the Dursleys (Fiona Shaw and Richard Griffiths), who stand near the door. (00:14:25)
Continuity mistake: After Harry thanks Hagrid for his birthday cake, Hagrid sits on the couch. In the next two shots facing Hagrid as he pulls out his 'umbrella', Hagrid's fry pan suddenly lies on the couch, which is visible to his right. The way he pulls out the 'umbrella' and the position of the fry pan differ within the two shots. Moreover, the fry pan is gone after these two shots. (00:14:25)
