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)Casual Person
Other mistake: At the beginning, when one bad guy is sitting on a bench with a newspaper, we can read the date October 21, 1959 at the top. But, we also read Nov 3 1970 on the same page, under the mugshot of the Boss being released from jail. (00:04:20)
Audio problem: At the scene where Mikey asks the elder penguin if anyone surfs in Shiverpool, when he says,"You know you're standing on thin ice," his beak never moves.
Continuity mistake: It's shown in many scenes that the robot Gallaxar sends isn't particularly quick moving when it walks. But when it's chasing Ginormica around the city, even though Ginormica is sprinting away, it can catch her far more quickly than its speed would allow. It doesn't suddenly speed up - in the shots when the camera focuses on the robot again, you can still see it moving slowly.GalahadFairlight
Plot hole: The newspaper headline showing young Alex being rescued from a crate is dated April 8, 1972. In the next scene, we see young Alex dancing in the Central Park Zoo, and watching him are Marty, Melman and Gloria as baby animals. This makes no sense at all. In the first film, Marty celebrates his tenth birthday. Key word: tenth. It is also known that the scenes of the main characters as adults take place in the present i.e. Alex confessing to breaking Marty's iPod. Seeing how the animals age quicker than humans, Marty, let alone his three friends, would have to have been born in the mid-1990s and the flashback scenes could not have taken place in 1972.
Continuity mistake: In the episode 'The 525 CrackerVac' the vacuum cleaner malfunctions (as usual) and Gromit challenges the device like in a duel. The scenery changes to orange like in a sunset and Gromit stands with his back towards the window. On the window sill you can see a cactus. Wallace is in the room near the door. The vacuum cleaner explodes and covers Wallace in ashes/dust. Wallace suddenly has the cactus on his head (also covered in ashes) and judging by the fact that there is a clean area behind Wallace on the wallpaper in the shape of Wallace with a cactus on his head he must have had the cactus on his head before the explosion, but we know he hadn't as the cactus was standing behind Gromit and Gromit stays clean after the explosion, so the cactus couldn't have moved. How did the cactus end up on Wallace's head?
Continuity mistake: Look carefully at the brochure Frank has about the Buffalo Chicken Wing festival, the building pictured is the same building as his daughter's school (seen earlier in the movie).
Continuity mistake: Lady is put in her bed and the master leaves the kitchen but he goes back in and puts a newspaper on the floor and leaves again but Lady gets out of her bed so the master comes back once more and puts her back in her bed but the newspaper on the floor has vanished.
Continuity mistake: The scene where Col. Hathi inspects his troops, he leans on his stick and it breaks. However, in the next scenes, the stick you see is sometimes broken and sometimes it is still complete.