Continuity mistake: Errol makes a mess with the chips and when Ron deals with the Howler, the mess on the table differs depending on the camera angle. For example, when the Howler says, "Ronald Weasley! How dare...," there is one kind of mess and then when it says, "..and it's entirely your fault!" there is another mess, but when the Howler shreds itself, the mess is the same as the first shot. (00:34:00)
Revealing mistake: After Harry yells, "Wood, look out!" Harry ducks to avoid the Bludger and flies away. In the following close-up of Harry, there are two reflections in each of the lenses of his glasses. The reflections were added deliberately for this shot, however, as he sweeps around the pitch, changing direction as he goes, the reflections should reflect the change in scenery around him, but it does NOT. (00:54:35)
Continuity mistake: In the dueling scene with Snape and Lockhart, when Snape says expelliarmus then does his wand movement, the camera leaves him after he has stopped moving his wand to look at how it goes after Lockhart, you can see Snape still in the background and he has not finished moving his wand. (01:05:35)
Continuity mistake: In Dumbledore's study, after speaking with the Sorting Hat, Harry walks toward Fawkes. As he passes Dumbledore's desk, on the corner of the desk there are some books lying on the side of the crystal ball. Then in the overhead shot as Harry says, "Your bird... He just caught fire," the books lie diagonally at the corner in front of the crystal ball. (01:14:50)
Continuity mistake: After arriving at Diagon Alley, Hermione runs up to Harry and Hagrid. In the wide shot as she says, "Harry!" there is a man with a red hat, holding an owl, to Harry's left and hanging in the doorway are beads that are pulled to the side door frame. In the close-up when Hermione says, "It's so good to see you," as that man enters the store the beads are hanging straight down. The beads are pulled up again in the next wide shot when they say goodbye to Hagrid. (00:17:25)
Continuity mistake: When Harry stabs the diary, it is completely soaked in ink, but when Professor Dumbeldore shows it to him it is partially dry. I doubt that Harry had time to escape the chamber, try and wash off the ink, and go to Dumbeldore's office. We see that stabbing the diary renders it powerless, so it can't have soaked up all the ink.
Continuity mistake: When Ginny runs downstairs to ask her mum for her jumper, the boys are eating breakfast at the table, Harry and Ron are sitting on one side, and directly opposite them are Fred, George and Percy sitting on the other side. When they are joined by Arthur Weasley, who sits at the head of the table, as he speaks to Harry and the boys we see the empty space, an unused knife and fork on Arthur's left hand side, though the twins were sitting there eating breakfast, as was seen previously. When Errol comes with the post, the twins are seen at the end of the table once again eating their breakfast, opposite Harry and Ron. (NOT visible on the DVD widescreen) (00:12:40)
Audio problem: When Harry, Hermione and Ron discuss Tom Riddle and Hagrid's supposed link to the Chamber of Secrets Hagrid overhears something and asks if they were talking about him. Harry, Hermione and Ron all turn round and we hear them say, "No!" at the same time. If you watch carefully, Hermione says, "No!" slightly afterwards, but no sound comes out. The line has been dubbed so that they all say it in unison. (01:30:16)