Continuity mistake: Rumpelstiltskin looks completely different in this movie than he did in the previous film Shrek The Third; Prince Charming momentarily talks to Rumpelstiltskin in the tavern during the third film, and the character looks completely different, has a different voice and different demeanor.
Continuity mistake: During Andy's daydream at the beginning of the film, Mr. Potato Head has an eye patch over his left eye. When the daydream cuts back to reality we see that Andy has removed Mr. Potato Head's left eye to symbolize the eye patch. But when Andy's mum comes in with the video camera, his left eye is suddenly back in. (00:01:15 - 00:05:25)
Continuity mistake: When Alice leaves to think over Hamish's proposal and chases after the White Rabbit, the heels on her shoes change, but when she falls into the hole the heels are back once again.
Plot hole: When Astrid gets on Toothless for the first time, Toothless takes off uncontrollably and tries to scare her. Hiccup seems to have no control over him at this time. How is that so if with the new tail fin, Toothless cannot fly without Hiccup's precise control of the tail fin? That whole sequence would have fallen apart. This mistake was even admitted to on the DVD commentary. (00:53:35)
Continuity mistake: Just before Flynn cuts off Rapunzel's hair, there is a shot from behind him and he reaches up with his right hand to push her hair behind her ear. His arm is visible up to his forearm and the shackle is nowhere in sight. However, in the next, wide shot, the shackle is suddenly up around his wrist. (01:01:20)
Other mistake: Before the battle, the leader of the waterbenders says that he will have everyone extinguish as many sources of fire as possible. When the firebenders come up from the ground at the start of the battle, all of the torches lighting the city are lit.
Continuity mistake: As Darren passes the cheese touch to the girl, she turns around in shock. In the next shot, she is standing still with everyone crowded around her running away, and Darren is no longer seen.
Continuity mistake: When the karate kid first goes to Mr Han's house to train, he drops his jacket by the doorway. Later on as they are talking, you can see his jacket move to different spots on the ground between shots.
Other mistake: When the ride finishes, there is no sign of a safety bar in Gru's cart.
Continuity mistake: When passing the lion in Trafalgar Square approx one hour in, the motorcycle sidecar swaps sides.
Continuity mistake: Whenever Megamind or Minion uses the disguise generator, their normal eye colour always show through their disguises, such as when they both disguise themselves as the Warden (the Warden has blue/gray eyes while Megamind has green and Minion has brown). However, during the final battle, Minion disguises himself as Megamind but he has Megamind's green eyes instead of his normal brown eyes.
Continuity mistake: In the second scene where we first meet ranger Smith he is shuffling with some information pamphlets. When Ranger Jones yells his name he is startled and drops some of the pamphlets, but we can see that the last ones he put in were on their side. When the camera changes shots there appears to be some pamphlets sticking out. Then in the next shot they are gone. The pamphlets change locations between shots.
Continuity mistake: Baby Roberta spits a mouthful of half-chewed peas onto Ramona's face. In the immediate close-up, there is much more green mess on her face than in the preceding shot.
Visible crew/equipment: When Bob, and the children go to the Chinese restaurant, a crew member and boom mic appear in the reflection on the car.
Continuity mistake: After Marmaduke squishes the toothpaste, the amount on the wall decreases between shots.
Continuity mistake: After the children are transported to Narnia, Edmund's hair is significantly shorter than it was while they were in England.
Continuity mistake: Carrie's skateboard is broken in half after she sneaks off with Flicka to ride it in the city. Later, when she's sitting on the couch depressed about Flicka being gone, the skateboard is in perfect condition. Adding to this is when she gets a new board near the end of the movie. (00:58:00 - 01:14:00)
Revealing mistake: Throughout the film the actors' breath is visible. This wouldn't be happening during the summer when the film is set.
Continuity mistake: When the security guard opens the back of his vehicle the gun is pointing to the left, but when the shot changes as the security guard reaches in for the hat, the gun is pointing to the right. Then as he turns to put the hat on Tyler, the gun is again pointing to the left.
Other mistake: The protagonist is still a kid, and she is telling in voiceover about all the things she vows to renounce hoping to have her dad back in health. On the porch she knocks repeatedly on the wood, but the magical numbers don't appear. (00:05:00)