Continuity mistake: At the start, when Data practices with the blue suction dart, in the close-up as the dart flies out we can see the mechanisms inside Data's invention. When it cuts to a tighter close-up, suddenly there is a spinning spool welded inside, which was not in the previous shot, that is retracting the orange string. (00:03:50)Super Grover
Continuity mistake: When Andy begins to lose it in the tunnel, Brand holds one lit lantern at the head of the line and Mouth holds another lit lantern at the back of the line (Mikey holds an unlit lantern). Next shot the lit lanterns have switched, just as they reach Chester Copperpot and Andy screams. Then in the next wideshot before it pans to the skeleton, the lantern Brand holds up switches yet again. (00:53:15)Super Grover
Continuity mistake: When Brand tells the others that the $50 bills are fake, Stef takes the newspaper with the Fratelli family mugshots off the post, from over the telephone. Then when Chunk gets the ice cream out of the freezer, the newspaper is back up on the post, but when the kids lift the dead body off the floor, the newspaper is missing from the post. Finally, in the shot just before Chunk shouts, "Guys, I'm stuck with the stiff," as the kids run into the fireplace, the tired newspaper is now lying on the printing press. (00:42:45 - 00:45:15)Super Grover
Continuity mistake: When Mrs. Walsh shows Rosalita the house, the attic door is open and we see that it opens at the left, with the wallpapered wall behind it and nothing in front of it except the banister. When Brand opens that door and the boys rush up, we see the wallpapered wall behind it, only this time the attic door opens at the right. (00:11:25 - 00:13:50)Super Grover
Other mistake: At the end, Mouth goes up to Stef and thanks her for offering to save his life. During the movie, however, Stef never offers to save his life. It is explained somewhere that in one of the deleted scenes, when Stef and Mouth are on the plank she offers to share her breath with him so they can both breathe under water.
Revealing mistake: After dropping the frame and breaking the glass, in the close-up of Chunk's arm removing the map from the frame, the arm is larger and much older looking - note the wrinkled elbow and thin arm/hand, whereas Chunk's elbow has puckers at the joint and he has short and chubby arms/hands. (00:16:15)Super Grover
Other mistake: In the scene where Mikey, Brand and Mouth are listing the exaggerations Chunk has come up with, Mouth says "And I bet it was even more amazing than the time you ate your weight in Godfather's Pizza." When he gets to the "Godfather's Pizza" bit, it becomes clear that this has been dubbed over the original filmed scene, as his mouth does not match his words in the slightest.