Corrected entry: When Harry, Ron, and Hermione are hiding from Filch, they find Fluffy, scream, and run away. But when they are speaking of it later, Hermione says something like "Honestly, don't you two have eyes? Didn't you see what it was standing on?" But it never shows Hermione looking down at the trap door when they were face-to-face-to-face-to-face with the three-headed dog.
Corrected entry: In the scene when Harry, Ron, and Hermione visit Hagrid, Malfoy is visible through the window. He appears to be eye level with the window and is shown turning and running away. When the camera zooms out later in the film, the same window that Malfoy is supposedly looking through is far too high for anybody to see through without a ladder. He obviously didn't have a ladder or he would have fallen off it when he turned to run away.
Corrected entry: In the first scene Professor McGonagall's broach disappears and reappears several times.
Corrected entry: Hagrid appears at the hut on the rock to fetch Harry on Harry's 11th birthday, which is July 31. The next day they go to London to buy Harry's school supplies, then end the day at King's Cross. But the letter Hagrid hands Harry at the hut (in the book, anyway - and in the film if you stop it to read what Harry doesn't) tells him to report to the train on September 1. What happened to the month of August?
Corrected entry: In all the shots of Snape that show the area around his feet, his cloak is either dragging on the floor behind him or gathered about his feet showing that it is quite long. However, after he wishes Harry luck in the Quiddich game against Slytherin, when he walks away the cloak is short enough in the back so Harry can see his limp from being bitten by Fluffy.
Corrected entry: Dudley is supposed to fall into the water in the Reptile House, which is obviously the one at London Zoo, yet he arrives back at his home in Surrey still shivering and wet. He would surely have dried out a bit on the journey home?
Corrected entry: This must always be a risk when working with child actors and filming out of sequence, but Daniel Radcliffe's voice obviously started to break during filming. It was most noticeable during the scene in the forest when his voice went from high to low to high again (and again, and again...)
Corrected entry: During the final chess game when the Queen is moving into position to smash Rons knight, they cut back and forth from the Queen to Ron. During one cut, the queen figure has its fingers laced and sticking out; in the next shot, one hand is a fist being covered by the other hand. Then it cuts back to outstretched laced fingers again.
Corrected entry: When Quirrell reports that there is a troll in the dungeon then faints he is laying one direction, but a few seconds later from a different shot he is laying the opposite direction.