Other mistake: Even though it is snowing throughout much of the movie, none of the snow seems to stick to any of the characters' fur. Even during the fight scene when they are rolling around in it, they are never covered with white.
Continuity mistake: When the Powerpuff Girls use their laser eyes to make windows in their room, the windows are oval. Later in the movie, such as when the Powerpuff Girls are sleeping the night before 'The Day', the windows are circular.
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: When Dr. Doppler and Jim first observe their ship, Dr. Doppler is right next to Jim when he points it out. When the shot changes to a long shot, they're much farther apart. (00:16:55)
Continuity mistake: When the King enters the castle a bowl of chocolate pudding is dropped on his head. You can clearly see the pudding run down his face, however when the bowl is removed from his head the bowl is completely empty and the King is totally clean. (00:19:55)