Revealing mistake: When Woody falls out of the closet wrapped in the string lights he hears Buzz's voice, and in the next shot as Woody sneaks up to Hannah's room we see Sid's open door and doorway, which looks perfectly normal. However, after Woody rescues Buzz from Hannah's tea party they both stop in the hallway, and there's another shot of Sid's open door and doorway, only this time it's not normal to say the least. Five of the six hasps, bolts, and locks that should be (and normally are) screwed into and attached to the inside of Sid's door (one hasp mechanism, third one down from the top, is attached to the door's frame) are now actually kind of floating there in mid-air right beside the doorway, as if there's an invisible door there. Weird that Pixar artists deliberately did this, but it's bizarrely funny to see.
Revealing mistake: When the weasels are at Eddie's apartment and Roger is handcuffed to Eddie, Roger runs under the bed and drags Eddie on the floor. As he pulls him you can clearly see a board with wheels under Eddie that is pulling him under the bed. (00:38:50)
Revealing mistake: When Madame gets off the carriage, Frou-Frou winnies to get her attention. Madame then proceeds to feed her. Frou-Frou eats from her hand. However, if you look closely at Madame's hand, it is empty. (00:03:05)
Revealing mistake: When the Pterodactyl is flying around with the egg, its shadow isn't cast as she flies over the trees.
Revealing mistake: When the elephants are making fun of Dumbo in the train caboose, Dumbo's mother pulls a pin which causes the stall door above the other elephants to fall. When the door bounces back up, you can see that the animators forgot to draw the elephants' heads and trunks and only their bodies are visible.
Revealing mistake: The stepmother's arm disappears for a split second when she tells her daughters that there is still a chance for them to become the princess.
Revealing mistake: After Helen finds the hair on Bob's suit, she goes to him while he is in the car and says," Have a great trip. I love you, so much.", Bob backs the car out of the driveway. He backs out and turns, but you can see his hand on the top of the steering wheel doesn't move. (00:47:05)
Revealing mistake: Near the end, right before Nita goes after Kenai, she takes off her dress. If you look closely, when she takes it off, her necklace and earrings come off with the dress as if they were a part of the dress. Also, her hair is tied back when she's wearing the dress. But when she takes it off, her hair is loose and flowing.
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)
Revealing mistake: When Tom is startled to hear "Rock A Bye Baby" on the phonograph, the whiskers on the left side of his face disappear for a frame or two.
Revealing mistake: In the scene where Rocky and Bullwinkle are walking through the university with Kenan and Kel (right before they come across the anti-moose protest), Kel's right arm passes through Rocky's left several times.
Revealing mistake: When Ratigan is sneaking up on Basil inside Big Ben, there is a shot where both characters have their backs to the camera. In this shot, there is a piece of equipment directly in front of the turning gear they are standing on. This piece of metal can be seen to flicker for a few moments.