Continuity mistake: When Harry, Ron and Hermione go to the third floor corridor for the first time, they all run into the corridor with Fluffy in and close the door. In the next shot, Ron walks through the door again and closes it again. (00:59:40)
Visible crew/equipment: When Harry, Ron, and Hermione are struggling in the Devil's Snare, a puppeteer can be seen on the left of the screen, working at least some of the masses of tendrils. (01:52:00)
Revealing mistake: During the chess game the Queen attacks the Knight's horse that Ron sits upon. In this close-up just before the spear actually hits the side of the horse, the large hole, used to aid the stunt, is visible in the belly of the horse between the stirrups towards the hind legs. This hole is not in previous shots. (Visible in fullscreen DVD.) (02:05:10)
Continuity mistake: When told to relax in the Devil's Snare, Ron's hands keep changing positions instantly. (01:52:00)
Continuity mistake: When Quirrel collapses in the great hall on Halloween, his feet are quite far apart. Camera cuts to everyone rushing for the door, and Quirrel's feet are practically touching. (01:05:30)
Continuity mistake: When Harry is telling the others that Snape gave Hagrid the dragon's egg, there is a group of older people walking towards them. They start to pass Harry, the camera changes angle and they are just starting to pass Harry again. (01:47:50)
Continuity mistake: In Harry's first Quidditch match, Gryffindor scores the first goal, then we see the commentator announce the goal and change Gryffindor's score to ten - making a goal worth ten points. Soon after, Gryffindor score again. We then see Slytherin score a goal, then another. They then score a third goal, and the commentator changes the score to 20 all, but it should be 20/30. (01:17:40)
Continuity mistake: When Hagrid goes to leave, the door has a gap visible at the top where you can see the rain. When Hagrid grabs hold of the top of the door the gap has vanished. (00:17:20)
Continuity mistake: When Fluffy drools on Ron, the amount of drool changes drastically. (01:51:30)
Continuity mistake: The amount of shirt that is untucked on Ron just after their exams is constantly changing from a lot to a little. (01:46:20)
Continuity mistake: When Neville first takes off during the 1st flying lesson, Ron covers his face with his right hand. When the shot changes, his hand is no longer over his face. (00:54:20)
Continuity mistake: On his first night in the castle, Harry is sat on a window ledge with Hedwig. In this shot, his feet go from resting on their sides and crossed at the ankles to flat and uncrossed. (00:48:50)
Visible crew/equipment: As the first years amass at the top of the steps prior to being sorted, a strong, round white light is in the glass behind McGonigal. (00:38:10)
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: 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)
Suggested correction: This is not a mistake. The letters are magically arriving en masse, in batches, pouring in at a rapid speed, and are flying about everywhere. Some naturally are facing up and others are face down as they come through the letter slot.
Visible crew/equipment: When Dumbledore gives the order to the students to follow the Prefects towards their dorms after the troll came out from the dungeon, just a moment before Harry warns Ron that Hermione is unaware of what is happening, some light reflectors simulating lightning are reflected on the glass above the pathway where the students come from. (01:05:55)
Revealing mistake: When Ron is hit by the Queen during the chess game, the stunt double is visible on the horse just a few moments before he falls. (01:59:00)
Other mistake: Albus Dumbledore's name is spelled incorrectly on his card (after the chocolate frog escapes the container). It's spelled with an "E." (00:36:00)
Audio problem: When Harry says "They're my letters, get off me!" to Uncle Vernon during the house flooding with letters scene, his voice is much deeper than in the rest of the film, and his mouth doesn't move. It indicates that this line was overdubbed long after main production when Daniel Radcliffe's voice had already begun to change. (00:11:40)
Continuity mistake: In the scene following Harry's sorting, Hermione has changed sides at the Gryffindor table. (00:43:00)
