Revealing mistake: When Harry and Hagrid are at Gringotts and are pulling up in the cart to Harry's vault, in the overhead shot you can see the various levels bellow them. In the next shot in the lower left corner you can see what appears to be blue screen just bellow the walking surface. (00:22:10)
Continuity mistake: When trapped in the Python exhibit at the zoo, Dudley stands up, presses his wet palms on the glass and nervously bangs on the glass while dripping plenty of water on it. However, in the next two shots after yelling, "Mummy, help! Help me!" the glass is all dry and just wet beneath his palms. (00:07:50)
Continuity mistake: When Hagrid and Harry step out the back door of the Leaky Cauldron, in the overhead shot there are many glass bottles on the floor, between the barrels. However, after Hagrid says, "Welcome Harry, to Diagon Alley," as they walk out the barrels are visible behind Hagrid and there are no glass bottles between the barrels. The stone ground differs in both shots too. (00:20:05)
Continuity mistake: In the scene straight after the Quidditch match where Harry, Hermione and Ron are telling Hagrid about their suspicions of Snape, you will see all three are wearing scarves tied in different ways. When there's a change of shots, the creases in the scarves change. This happens mostly with Hermione's. (01:23:55)
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)
Continuity mistake: After leaving Gringotts, Hagrid directs Harry to Ollivanders to buy his wand. When Hagrid says, "Why don't you run along there and wait...," there is a close-up of the store. Under the name Ollivanders the three roll window shades are completely pulled up, allowing the lamp chain to be visible behind the curved showcase window and the window shade at the top of the front door is pulled partially down behind the glass panes. However, as Harry opens the front door in the first shot, the window shades to his left, in the curved showcase window, are partially pulled down and the window shade on the door is now rolled up. (00:24:50)
Continuity mistake: In the scene where Harry and the Dursleys visit the zoo, the first shot you see of the snake, he is lying on a bare rock with only moss on it. He is also lying with his head facing the window, and his body is curving to the right. However, after Dudley walks away and the shot returns to the snake, his body is curving to the left and now there are plants directly behind him where there was only moss before. (00:06:00)
Factual error: The Hogwarts Express leaves from platform nine and three-quarters, between platforms nine and ten at King's Cross station, London. The platforms shown in the film as nine and ten are, in fact, four and five (the only platforms that have a wall between them as shown in the film). The real platforms nine and ten are in a separate part of the real station. In addition, when Hagrid and Harry are on the footbridge, they are walking towards platform one, away from both the real platforms 9 & 10 and the film's platforms 9 & 10. No wonder Harry feels lost when Hagrid leaves him to find the train on his own! (00:31:55)
Continuity mistake: In the sea hut scene, when Dudley steals the cake, there's a shot of him eating it and his pyjama shirt is pulled up, then it cuts to Hagrid, and he says 'He'll be under the finest headmaster...' and it cuts back to Dudley, but his pyjama shirt is back down over his pyjama pants. (00:17:10)
Continuity mistake: While the first years are waiting at the top of the stairs just before being lead into the Great Hall for the first time, Ron's robes switch from being fully opened, to closed, then back again. (00:40:00)
Other mistake: In the scene where Professor Quirrell removes his headwrap to reveal the concealed Voldemort, Quirrell is obviously bald. However, if you carefully watch the scene with the troll, Quirell's sideburns are present after he shudders as the troll exhales, as they are in a couple of other shots. (01:10:43)
Suggested correction: The incident with the mountain troll took place on Halloween. The incident with Quirrell took place later in June. That is plenty of time for Quirrell to shave his head. Makes sense that he would as, I mean, I would rather shave my head if there was a guy on the back of it! Then I wouldn't have to worry about bumping his nose and him getting mad at me while using a comb. To be a mistake, we would need to see him with hair right before he is bald.
Continuity mistake: When Hermione is saying to Harry and Ron "You won't make a fool of yourself, it's in your blood," Harry and Ron have several books with them, but straight after, right before the staircase moves, they have no books in their hands. (01:00:35)
Continuity mistake: On Dudley's birthday, when Mrs Dursley wakes Harry and he sits up in bed, a cloth and hand brush are hanging next to him on the inside of the cupboard door. When Dudley shoves Harry back into the cupboard, there is now a cloth and a dustpan, but no brush. When the family arrive back from the zoo, and Mr Dursley locks Harry in the cupboard, there is no cloth, brush or dustpan. (00:04:10)
Continuity mistake: At Kings Cross, just as Percy Weasley is about to run through the wall onto platform 9 3/4, we see a man and a woman walking past him, but when the shot changes direction, they have both disappeared. (00:31:15)
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)
Other mistake: During the Quidditch match, Hermione looks in her binoculars up to where Harry is. If you look at the reflection in the binoculars, you can see Harry flailing around. She then looks over at Snape, but when we see the reflection in the binoculars, we still see Harry, as if she was looking up towards him. (01:20:40)
Continuity mistake: When Harry, Ron, and Hermione are heading to Hagrid's hut after discussing the stone, Harry says 'Why didn't I see it before?' his tie is all the way over to his right side, then when they are talking to Hagrid his tie is straight in the middle. (01:46:00)
Continuity mistake: When Harry raises his hand with the captured Snitch, his back faces the Slytherin and Hufflepuff towers which are opposite each other, with the hoops between them. However, in the next shot he is now facing that side of the pitch, as other Quidditch players appear from that side. (01:23:25)
Continuity mistake: The knotted tie string on Harry's Quidditch robe changes from extremely loose, to snug, to loose and so on, even in consecutive shots, from the time Harry speaks with Wood before they fly onto the pitch and throughout the match. This occurs with other members of both teams as well. (01:15:40)
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.
