HARRY POTTER AND THE SORCERER’S STONE
1) Book title changes between shots
Harry’s book named “One Thousand Magical Herbs and Fungi” suddenly changes its title to “One Hundred Magical Herbs and Fungi” later!
2) Four names called out instead of three
During the scene where the little wizards were being assigned to different houses, it was shown that only three were left to be assigned. Professor McGonagall calls out four names though.
3) Visible wires through which the candles were suspended
In the scene following the one in which Quirrell announces the presence of a troll in the dungeon, the wires that were used to suspend the candles mid-air are clearly visible.
4) Ron’s hair changes from centre-parted to side-parted between shots
While Harry and Ron were on the train, Ron was shown to have centre-parted hair initially. Later, the parting shifted towards his right.
HARRY POTTER AND THE CHAMBER OF SECRETS
5) Visible cameraman among the actors
During the scene where Snape helps Malfoy onto his feet, a cameraman is visible, kneeling among the little wizards towards the far left.
6) Shirt goes from unbuttoned to fully-buttoned up automatically
While Harry, Ron and Hermione were having the Polyjuice Potion, Harry’s shirt is shown to be half unbuttoned when he starts to gag. The scene cuts off to a later stage after that. When the scene resumes later, Harry’s shirt is shown to be all buttoned up.
7) Visible safety tip on sword
During his fight with the Basilisk, Harry’s sword has a safety tip, which is clearly visible on close observation.
HARRY POTTER AND THE PRISONER OF AZKABAN
8) Visible bulging power packs
When Hermione and Harry go back in time to save Buckbeak, their power packs for the cordless mic are clearly visible from under their clothes as a small rectangular bulge!
9) Perfectly clean ground becomes messy in the next shot
During the scene where Sirius flies away on Buckbeak, the stone ground is shown to be perfectly clean. However, when Harry and Hermione run across it, the same ground is covered with dead leaves and mud all of a sudden!
10) A single-hand push gets transformed into a double-hand push in the next shot
During the scene where Tom pushes Harry to the chair, you can clearly see him pushing him with a single hand. In the next shot, though, he seems to have used both his hands.