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?
Other mistake: When Heather Hills takes a swing at Rodrick with mike stand and hits the chocolate fountain, how does Heather splash chocolate on herself?
Revealing mistake: When Alex says they should go find the penguins, he says "To home" and Marty, Melman, Gloria and Julien place their hands on top of his hand. In the next shot it shows all of them together. But due to the position of Julien and his arm length, it would have been impossible for Julien to have his hand fully placed on Alex's hand. (00:05:05)
Factual error: Johnny shows Mavis the sunrise by keeping her back in the shadows. But if your whole body is in an object's shadow then you can't see the light source. The rising sun is reflected dead center in Mavis' eyes, which means the sunlight is touching her, which means she ought to be on fire.
Continuity mistake: The driveway is clear of snow the day the Baxters move in. Based on the amount of snow in Mason's yard (across the street) and other outside views, there has not been a snowstorm after the Baxters have settled. In fact, the wet roads and melting snow on lawns indicate an ongoing thaw. Christine (Finn's mother) tells the kids they will be leaving to go shopping for a tree and decorations as soon as Curtis (Finn's father) finishes clearing the driveway. Curtis is then shown struggling to use a snowblower to remove A LOT of snow from the driveway (which had been clear of all snow on move-in day). (00:00:58 - 00:18:51)
Factual error: The pirates' map shows a drawing of Tower Bridge, which Pirate Captain sees through the telescope moments later. Construction of Tower Bridge started in 1886, and it was completed in 1894. Queen Victoria was 73 when Tower Bridge was completed, whereas she is in her late twenties or mid thirties here. The sign setting the film in 1837 also makes no sense given this timeline. (00:25:20)
Plot hole: When they find captain Nemo's journal the journal is completely intact and the pages are made of paper. But the journal is very old, and the island sinks every 70 years, so the journal should not have looked that good, and the pages must be gone by now or at least not that readable. (00:47:30)
Other mistake: When Ida is with Prince, in some of the closeups Prince is wearing a custom halter noseband with "Sky High Angels" embossed on the leather. The "Sweethearts of the Rodeo" rodeo stunts featured in the movie were performed by the "Sky High Angels", a real rodeo drill team, and Prince was played by Hank, an equine member of the "Sky High Angels."