Other mistake: In the intro to the Pastoral Symphony, the narrator identifies the deity who cloaks the world with Night to be Morpheus, who is the Greek god of sleep and dreams. However, the character in the animation is fairly obviously female, with long hair, eye shadow, and lipstick. My theory is that the character was intended by the art team to be Nyx, the Greek goddess of Night. Night would be a more likely candidate to be making it nighttime across the world, while Morpheus would be more likely to put people to sleep or send them dreams.
Suggested correction: Without further evidence/proof, this theory remains just that. A theory.
Continuity mistake: In the scene where Grug is chasing after Guy, they both wind up stuck in a tar pit. After successfully escaping they are covered in tar and Grug even gets himself stuck to Guy. In the next scene everyone is running from the exploding ground up between the mountains and both Grug and Guy are completely clean and free of tar.
Factual error: A toy modern four-door automobile and a clear plastic ball can be seen as the children play when the Burgermeister comes in on his wheelchair. Both unlikely for a story set (presumably) in the 1800's, at the latest.
Audio problem: On the first level of the video game, after Velma brings up what she remembers what Eric said about the Scooby snacks in the game, you hear Daphne talking but you see Velma's lips moving. (00:01:00)
Continuity mistake: When Barry gets stuck inside for the first time, he hangs onto the drapes. His arm is straight across, but in the shot behind him, his arm is now bent and raised and above his head.
Factual error: In the beginning of the film, the Dowager Empress Marie states that the year is 1916 and that they are celebrating the 300th anniversary of their family's rule. The 300th anniversary actually took place in 1913. (00:01:05)
Other mistake: After Terrance shows the painting of Matilda and she runs off, if you keep an eye on Terrance as the screen pans upwards when there isn't a lot of his body left, he randomly disappears when the pigs appear in the shot.
Deliberate mistake: In the scene where Emmet drives to work, you get Emmet's view of the dashboard with his hand switching on the radio. The car at that moment has no front window, perhaps to make the car look bigger from the inside. (00:04:50)
Continuity mistake: After the ball game, there is a cut over Miguel's eyebrow. Right after this scene, the cut has disappeared.
Audio problem: During the Tea Party scene, the Mad Hatter and March Hare ask Alice to tell her story. After the Mad Hatter says "And when you come to the end, stop!" audio follows of the voice director saying "great," leftover from the original recording. (00:45:40)
Continuity mistake: When Toad General calls for the council's attention and announces that Bowser found the Super Star, note his shirt buttons. Then, when he says that the Kongs will never agree because their mad king doesn't make alliances, Toad General's shirt is backwards, his buttons are on the opposite side. (00:24:55 - 00:25:35)
Continuity mistake: When the butler takes the mother and kittens to be abandoned in the countryside he is on a motorcycle and sidecar combination. During the trip the sidecar changes from one side of the bike to the other and back again. Also, when the sidecar separates from the motorcycle when the dogs are chasing Edgar, the wheel on the sidecar switches sides regularly as well.
Other mistake: During the Battle of Teth (the pillared jungle planet), the AT-TE's shoot the ledge at the top and there's not a single mark on the ledge afterwards, despite being hit with several joules worth of fire.
Continuity mistake: In the scene where Aladdin is talking to Jasmine in front of the mirror the jewelled flower is in a vase with a real flower when the monkey under the table takes the real flower and the scene cuts back and shows the vase with both flowers. Seconds later the vase is completely empty.
Deliberate mistake: When Tarzan fights with the leopard, it scratches his chest. However after they fall into the pit and Tarzan comes out carrying the dead leopard, the scratches on his chest have amazingly healed. [It is a long-standing Disney tradition that no evidence of violence is shown on screen. Still a mistake, but there's why].
Factual error: When hero boy and girl and Billy are on the runaway car at the north pole, they crash into the stopper at the end of the tracks. They are flung backwards when in reality, due to inertia, they should have been flung forward into the guard rail.
Plot hole: Johnny's dad jumps in his truck and gets to Johnny in moments. That same journey was shown to be an overnight bus journey for everyone else.
Factual error: The main character from the video game "Paperboy" is among the alien invaders in the final battle; since that game was first released in 1984, he shouldn't be there, because the probe the aliens received featuring video game footage was launched into space in 1982.
Factual error: When the minions are attempting to purchase tickets to get in to see/steal the crown, the admission prices on the wall are priced as £s and pence (decimal currency). As this was 1968, Britain was still using pre-decimal pounds, shillings and pence.