Deliberate mistake: At the beginning of the Fellowship's journey, they are resting on a hilltop (Hollin) with rocky formations. Bill the pony is tethered in the background in one shot. Then come the spying crows from Saruman and they all quickly hide. When the crows swoop in closer we see no-one, but who hid the pony and where? (01:37:45)
Deliberate mistake: When Elliott and ET are on the bike heading to the forest on Halloween night, ET is covered with the white sheet, but in the closeup of ET's face right before the bike flies he's covered with the white blanket (note the material), which is from the scene later in the movie.
Deliberate mistake: When Harry drops the Monster Book of Monsters, in the first shot facing Harry's feet as the book chomps at him, he runs backwards a few steps and he stands at the foot of the bed. However, in the shot facing the fireplace, there is actually plenty of floorspace now, much more than other shots, between the rug and bed for Harry to continue to run backwards. (00:15:15)
Deliberate mistake: When "Legs" lowers the Pez duck named Ducky down through the removed lightbulb hole, to ring the doorbell, the lightbulb housing is bigger than the hole but they bring it up through the hole to remove it. (01:03:55)
Deliberate mistake: In the scene after the Helm's Deep battle, when Aragorn meets Eowyn, the earlier footage of Aragorn's return to Helm's Deep is used. He has the wound on his shoulder and is dressed like he was during the 'falling' episode. The background (people in the fortress walking calmly) also indicates that this takes place before the battle. This scene should immediately follow the one where Aragorn is greeted by Gimli ("you are the most reckless man I ever knew"). Confirmed on cast commentary, extended DVD. (02:45:20)
Deliberate mistake: When Will is bound and brought before "Chief" Jack, Will says, "The compass!" and there is a close-up of the compass, as it hangs to the right of the long striped cloth. However, in all other shots the compass hangs to the left of the red and white striped cloth. This is a flipped shot - note the large buckles. (00:24:00)
Deliberate mistake: When the kids are about to jump start the trap Phoebe hides behind the school bus door. Half a second later, when the trap opens, she's nowhere to be seen, not even jumping or stepping inside the bus. Then half a second later she has managed to get inside, turn around and protect her head while the bus windows burst. It all happens in real time for their hairs are still fluttering. It sure paces up the scene, but it's really awkward.
Deliberate mistake: Not only is the angle of the moonlight that shines through Jack's prison cell window intentionally exaggerated to enhance the shots with Jack, doggy, Koehler and Twigg, but in relevant shots, the moonlight is not seen coming through the window or the broken wall. Nor is it reflected on the floor outside the cells or in the cell next to Jack, particularly in the shots from the dog's POV looking up the corridor towards Jack. (00:36:00)
Deliberate mistake: When Phil wakes up at 6 AM, it's already bright outside. At 6 AM in February, it would still be pitch-dark.
Deliberate mistake: In the Extended Edition, the location of the Tomb of the Stewards is shown to be behind the city of Minis Tirith, at the cemetery on the mountainside, accessible via a long bridge. Flaming Denethor later runs to the far prow of the city, leaps off and plummets. The distance between the two areas makes it is obviously entirely impossible for someone, even adrenaline charged Denethor, to run this distance while his oiled flesh burns. Admitted on the commentary that it's poetic license, due to director Peter Jackson's long awaited vision for this dramatic shot. (00:13:15 - 00:30:50)
Deliberate mistake: When Peter and Miraz are fighting, Peter stabs Miraz and then brings the sword back up for the killing stroke. There is no blood on the sword. This is deliberate on the part of Disney, so as not to show blood, but a mistake nonetheless.
Deliberate mistake: After the Tusken Raider has attacked Luke, he raises his stick over his head and shouts. The movement of his clothing is extremely unnatural. During the editing, they put the same footage forward, then backward many times, to add emphasis to his movements, but it looks decidedly odd. (00:29:02)
Deliberate mistake: When the Trunchbull is drinking from the glass with the newt in it, you can easily see that she doesn't actually drink anything, as the water level stays exactly the same. Logical, as the newt is real, but it's still very obvious because she drinks for about 15 seconds. (00:46:55)
Deliberate mistake: After Peter says, "We can't both have her lady," he shuts the window from the outside and the bottom pane is placed on the outside of the top stained glass pane. This is obviously done specifically for this shot so Peter would be able to shut the window and try to keep the Darlings from opening it. However, in the next shot as the Darlings succeed in opening the 'stuck' window, the bottom pane is on the inside of the top stained glass pane. (00:02:05 - 00:58:45)
Deliberate mistake: When Boo laughs repeatedly while playing hide-n-seek with Sully in the men's room, nothing happens to the electricity - no surges as with all other times she laughs. [In the audio commentary by the directors, they explained that it would've been distracting if an energy surge occurred every time Boo laughed, so they simply didn't address the issue. A reasonable course of action, but still a mistake.] (00:37:30)
Deliberate mistake: Spoilers! When Black Manta is defeated, he is knocked unconscious and tumbles down a rock face after his helmet explodes on his face into the waters by the shores of Sicily. These currents and waves at best would have carried him to the rocks or the beach, leaving him on land or near it. However in the after credit scene he's somehow found out in the middle of the ocean on a broken drift wood. He would not have been carried back out to sea like that.
Suggested correction: The water is tidal. If the tide was going out, the current would take him out to sea.
There are hardly any tides in the Mediterranean Sea http://scienceline.ucsb.edu/getkey.php?key=995.
Deliberate mistake: When Jar Jar gets arrested in the Gungan city, in the second shot of Jar Jar and Obi-Wan, Obi-Wan and a part of the floor behind him are reversed. This can be seen, for example, because two of the red areas on the floor have switched positions, and Obi-Wan's braid and lightsaber are on the wrong side. (00:14:00)
Deliberate mistake: When Jack fights the impostor, they are roughly the same height, but when the impostor is revealed to be Angelica, she is suddenly much shorter than him. (00:21:30 - 00:23:50)
Deliberate mistake: Obviously due to the family nature of the film, but when Peter stabs the White Witch's henchmen at battle, the sword always remains clean, and never bloody. (This is a Disney family film and as such no blood is shown. Still a mistake, but there's the reason). (01:56:10)
Deliberate mistake: In the first scene Velma gets sprayed by the hose and slips but gets her foot caught on the chain; hanging upside down, but her skirt doesn't go "up". Deliberate to maintain the "family movie" tone. (00:02:40)