Continuity mistake: When Kuzco and Yzma make a dive for the potion bottle, Yzma is turned into a cat simply by landing on the potion bottle. This suggests that a person only needs to touch the potion in order to be affected. However, when Kronk and Yzma are serving Kuzco dinner and are trying to avoid poisoning themselves, Kronk pours his potion drink on himself and is not affected.
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.
Continuity mistake: During the duel between Miraz and Peter, when they call for a time out, Miraz is shown in the background walking back to his generals and stepping onto a raised area. A few seconds later, over Peter's shoulder, he again walks to the raised area and steps up (there's only one step). (01:44:55)
Other mistake: When one of the agents is ambushed by the Tooth Fairies he is reduced to a skeleton, with his teeth still visible. However, it was earlier stated that Tooth Fairies start by eating the teeth, then finish off the rest of a body.
Visible crew/equipment: Throughout the movie, in the shots of the guys on the alien planet, the white reflector screens and film crew's reflections are visible in their sunglasses. (00:40:20)
Revealing mistake: In the library scene when Richie sees Pennywise the clown, all the balloons filled with blood are popping on people who aren't supposed to be able to see them, but one lands on a lady and you can see her jump as the balloon pops.
Continuity mistake: Darth Maul's neck is black, but when he is talking to Darth Sidious on Coruscant, his neck is flesh-toned. (00:38:45)
Continuity mistake: In the dormitory, when lovestruck Ron is going gaga over Romilda, he is wearing a brown sleeveless tee shirt and its tan trim has many holes. When Harry brings Ron to Slughorn, Ron is still wearing that tee shirt, but now some of the holes are gone and the rest of the holes have changed position. (01:26:50)
Revealing mistake: Mr Hyde makes no bubbles when growling underwater. (01:11:30)
Plot hole: During the scene where Merida gives her speech on "breaking tradition", her mother, as a bear, moves silently behind the majority of the crowd, so they don't see her. Fair enough. However, Merida and her father's clan are all looking in the same general direction (towards the crowd) while she's speaking - how does no one from Merida's clan see a bear moving at the back of the room?
Visible crew/equipment: Michael J. Fox is dancing on top of a bus as the Teen Wolf. The camera swings just a little too far toward the back of the bus and a police car that is escorting the camera car and bus is seen in the rear with its red lights going.
Visible crew/equipment: As Melanie drives up to have dinner at Mitch's, the reflection of the cameraman on the inside of the window can be seen moving in the upper-left hand portion of the screen. (00:32:10)
Continuity mistake: When the evil king's female assistant is "turned into" Odette, and Prince Derek is dancing with her near the end, he puts the locket on her. The chain goes around her hair, and in the next shot, it's under her hair. They were dancing the whole time, so how could she or Derek have pulled her hair out of the chain?
Continuity mistake: Once the chipmunks are inside the food cupboards, they begin to devour everything inside. Theodore is seen chewing off a corner of a box of Lucky Charms cereal and eating the cereal that pours from the hole. But a few shots later when the same box of cereal can be seen, the hole that Theodore gnawed from the corner of the box is gone and the corner is fully intact. (00:11:00)
Plot hole: So he needed the help of a big strong burly guy to flip the safe with the body, end over end to the pit, but he somehow was able to easily get it out of his basement and into the back of his car by himself?
Revealing mistake: When Brom (disguised as the horseman) throws the jack-o-lantern at Ichabod, there is a shot from Ichabod's perspective showing the jack-o-lantern flying toward him. It jiggles from side to side, revealing it was travelling on a wire.
Continuity mistake: In the scene where Jonathan picks up the scarab, it breaks open and the beetle inside starts to crawl under his skin. We see Brendan Fraser tear Jonathan's shirt and cut the beetle out of him. However, in the very next scene, we see Jonathan walking into the temple, his shirt is intact and there is no blood to be seen. (01:37:05 - 01:38:30)
Plot hole: When Alex and Clear are sitting and having coffee they are on a corner. He looks in the window to see the bus pass, and as he looks to see if it is there, it's not. As the camera pans across the street, there is some construction going on which is blocking that whole road from being used, but then Terry, Carter's girlfriend gets "waxed" by the bus - no way it could have got through all that construction.
Visible crew/equipment: When Ashley is running down the corridors before escaping back into her medical room, you can see the dolly that The Engineer chasing her is being pushed on. (01:04:50)
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)