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.
Continuity mistake: Carl's cop car has the licence plate "G2298" which is printed thinly on the licence plate. Then, when the vine wraps around his car, and bends it in two, the licence plate is now "CFJB95", printed very boldly on the plate. The words "POLICE 004" also differ, as does the bumper and the lights. Totally new car, methinks... (01:14:55)
Continuity mistake: When Wallace is put into his overalls he's still wearing his green pullover. A moment later he suddenly doesn't wear it anymore but a complete white shirt. He couldn't have just taken off the pullover as the shirt under it is actually fake (The collar is actually part of the pullover and the arms are just stuck on).
Continuity mistake: When Godfather Drosselmeier walks into Marie's bedroom before he tells her the story, the bedroom door opens from the left, but after Marie's mother brings her the breakfast tray the door now opens the opposite way, from the right.
Continuity mistake: In the parking lot scene we see Tommy get thrown through what appears to be plasterboard. When he goes through it leaves a big chunk still attached in a triangle shape. Camera cuts and what remains has changed and the triangle piece is not to be seen. (00:23:10)
Continuity mistake: When James and Kat first enter Whipstaff Manor, they drop their stuff on the floor. The large suitcase falls over on its side, but it cuts to the overhead wide shot and the suitcase is standing upright (the ghosts didn't do it). (00:19:45)
Continuity mistake: When Omri opens his birthday presents, Gilly's rat in the plastic ball is on the table; two seconds later it disappears.
Continuity mistake: When Pocahontas sees John Smith for the first time, John is climbing up a cliff face and then a tree. You can see his musket strapped to his back as he's climbing. But after he tells Thomas he's getting a better look and then is shown in the tree, his gun has vanished.