Mistakes

 Susan Bones was sorted into Hufflepuff house during the official sorting ceremony. In the movie however, we see her studying in Snape's Potions class of Gryffindors and Slytherins.

 Percy Weasley tells the Gryffindors that the girls dormitory is up the right staircase, while boys are on the left. However, the rule is soon violated after the leading trio stumble upon Fluffy and run back to the common room - Hermione runs to the left, while Harry and Ron are seen heading towards the right of the room.

 After being sorted in Gryffindor, Harry takes a seat next to Ron, on the right of the table. Immediately after we are shown the start of term feast and as if by magic, Harry has moved to the left of the table and is sitting adjacent to Hermione.

 After entering the third corridor, Fluffy promptly drools on Ron. After jumping through the trapdoor however, he is no longer covered in huge globules of liquid - instead, he's completely dry!

 Draco Malfoy appears eye-level at the window while Hagrid and the trio watch Norbert the Norwegian Ridegeback hatch from his shell. When viewing this window outside of the cabin, it is shown as much too high for anybody to peer through without a ladder. If Malfoy was using such equipment, it would have rendered him impossible to escape that quickly without hurting himself in some way.

 The camera crew make a cameo appearance in 'Harry Potter and the Philosopher's Stone.' While gazing into the Mirror of Erised and listening to Dumbledore's caution, the shadow of a camera and a poised individual appears magically alongside Harry.

 At the very end of the movie, Hagrid hands Harry a photograph album containing images of his parents from friends of the family. The next shot shows him walking towards the Hogwarts Express, but there's no sign of the album in his clutches - or anywhere else, for that matter!

 When our three leading characters are boarding the train, the trees on the left appear to be blowing wildly in the wind... but the trees on the right aren't moving at all!

 At the beginning of the movie, Hermione tells Harry and Ron and put on their robes as they will be arriving at Hogwarts very shortly. However, it is daytime outside - quite surprising how night falls so quickly, as it is very dark outside when they part the train.

 Hagrid hands a Gringotts goblin a very old and crinkled letter. When the goblin reads it however, it looks brand new, before transforming into the aged piece of parchment again.

 While in the girl's bathroom, the troll happens to destroy the second sink from the left. After the troll is knocked out with his own club, the camera zooms in on Hermione who asks whether the troll is dead. In this frame, we can clearly see the once-destroyed sink is perfectly intact.

 When the club falls from Ron's levitation, we hear a rather loud 'clunk' as it hits the troll's head. There's no sound when it hits the floor though!

 When Harry first enters Diagon Alley, we can see two witches looking at a store display of large lollipops. Harry then walks past them, but when the camera changes angle, he is seen to walk past them again.

 Harry confronts the real Professor Quirrel, who has large wounds on his face including a scratch on his chin. When Harry enters the infirmary at Hogwarts, this scratch appears to be twice as large as before. It then disappears to a state of bare visibility when Professor Dumbledore comes to visit.

 In Potions class, we see Harry writing notes while Snape is talking. At first, his writing appears very fine and cursive - when the camera angle changes, it is crude with block letters and has changed quite considerably in size.

 After running into the Hogwarts Great Hall and announcing a 'troll in the dungeon,' Professor Quirrel falls forwards and face first. When the camera changes its angle, it appears that Quirrel has flipped over, because it now looks like he has fallen on his back.

 A car is located outside the second house of Privet Drive while Dumbledore extinguishes the stree lamps. A few seconds later, and it's moved to the house next door.

 When Harry enters Ollivanders, an overhead angle shows three wands laid out in a fanned position. When the camera changes its angle to that of eye-level, the wands have been mysteriously straightened.

 When we first meet Dudley Dursley, a close up shows his one-inch fringe with loosely parted strands. In the next shot, it's all been gelled together.

 When Hermione tearfully exits the toilet cubicle, her hair appears crooked in the middle. When she hides under the sink just a few seconds later, that part of her hair is a perfectly straight line.

 After transfiguring from a cat, Professor McGonogall is not wearing her glasses. In the next shot, while talking to Dumbledore, she seems to have them on.

 When Fluffy eventually wakes, Harry moves aside to let Hermione jump down the trapdoor. In the next shot, from the bottom of the trapdoor, Harry has arrived first!

 During the ride on the Hogwarts Express, Ron's hair changes from a centre parting to a side parting.

 Towards the end of the film, the camera zooms past the Quidditch stadium to get a better look at the Hogwarts exterior. If you look closely, only the hoops are filmed - so where did the stadium suddenly vanish to?!

 When Percy leads the Gryffindors back to their dormitories the group is much, much smaller than the amount that sit around the Gryffindor table.

 Daniel Radcliffe's eye colour appears to change many times throughout the movie. From green to blue, and all the shades in between - this may be due to lighting angles, however.

 When Dumbleodre announces Slytherin's house cup victory, we see Draco Malfoy with his hair sticking out of his hat. When the camera changes angle and goes back on to Malfoy, it's all tucked under his pointed black hat.

 While Harry contemplates with Hedwig at the window of Gryffindor tower, we see his ankles are crossed while he sits in his pyjamas. When the camera zooms in, they no longer are.

 When the snake escapes from the reptile house at the zoo, it winks at Harry. This is quite impossible, as snakes don't have eyelids.

 Before the first-years have been sorted, all the house tables are completely full. During and after the sorting, they are much emptier, giving the first years somewhere to sit.

Credits to UK Harry Potter