Continuity mistake: When Eddie escapes the deep freeze, he wears three rings on his left hand: his middle, ring and pinkie fingers. Bizarrely, the pinkie ring actually disappears in quite a few shots, including when Eddie plays the sax and when he lifts Columbia, just before they mess around on the floor.
Picture submitted & edited by Super Grover
Continuity mistake: After Gerry gets smacked in the face by the 'broken' suspender clasp, we see the silver clasp land under the dresser. Yet, when he's moaning and lifting his leg to get onto the bed, we can actually see the clasp still intact on the front suspender that came loose, which is dangling right behind him (just look between his legs). Of course, in the next shot, that clasp is gone. Since the silver clasp is one of the plot points, this is bizarre to say the least.
Continuity mistake: When John and Catherine are in the hangar at the runway, the Cessna's tail number is N3035C. When the plane is shown in the air, the number is N3973F. When they land, the tail number has changed back to N3035C.
Continuity mistake: In the bedroom scene the girl is holding a clear cup full of beer. The camera goes off her and when it comes back she is holding a blue cup. The camera goes back off her then on her and the cup is clear again.
Continuity mistake: When Sam is in his bedroom, after he finds the Cube sliver it falls and dramatically burns a hole through the floor into the kitchen. But Sam's bedroom is over the living room (there is nothing on the ground floor below Sam's elevated bathroom, and in the first movie Jazz hides in this open space), and the kitchen is actually located between the den and dining room, at the other end of the house. If they were to follow the actual floor plan of the house, the Cube sliver would have landed in the area of the piano in the living room, but where would the fun have been in that?
Continuity mistake: A heavy rain is falling as Arlo and Spot are trapped in a rushing river. During close-ups of Arlo, the rain is falling at a sharp angle to the right. During close-ups of Spot, the rain is falling at a sharp angle to the left.
Other mistake: In the opening sequence, Mowgli is running at full speed through the jungle, accompanied by Basheera the black panther, who is mostly unseen until Mowgli finally collapses, exhausted onto the jungle floor. Mowgli lies on his back, talking to Basheera, and neither are breathing heavily or showing any sign of exertion following their lengthy run.
Continuity mistake: After the meeting with the ghost of the mansion Erin hugs Abby and she gets the ectoplasm from her, but in the next shot it disappears.
Factual error: When Apocalypse touches the television in Cairo and says he is "Learning", the next shot shows the rooftops with many smallish satellite dishes in view. This is set in the early eighties when satellite dishes for TV were much larger.
Continuity mistake: In an early scene with the Scrat on board the alien space ship, he accidentally increases the artificial gravity, and there is a control panel indicator with the word "GRAVITY" in English. In a later scene when the ship is out of control and a danger warning flashes in front of him, it's written in an alien language.