Revealing mistake: While Nick and his father are driving home with the giant baby behind (an obvious green screen projection), the baby breaks a tube from the car and throws it to the floor. Nick bends down to pick up a prop located offscreen, to add up for realism, but the problem is that he bends down before the baby throws it, so the whole trick is revealed.
Revealing mistake: When Marius is talking to Lestat on the beach, the victim that Lestat drops is a dummy. (00:24:05)
Revealing mistake: When the Grinch is cutting Max's antler, the cut lines appear on the prongs before he actually starts to cut.
Revealing mistake: Just before the end credits, as Superman is flying past Metropolis and into space, watch the car headlights in the background. The background shot is blatantly sped-up by a large amount, as all of the cars appear to be travelling at huge speeds, even in a traffic jam.
Revealing mistake: When Stiles enters the locker room, a guy walks out the shower and you can see his black underwear. (00:05:25)
Revealing mistake: During the wedding scene, while the narrator is talking, you can see the string that will pull the left table apart. As said in the commentary, the filmmakers weren't going for the idea of people pulling the tables apart, but rather some other force parting them. (01:27:40)
Revealing mistake: When Phil drives the truck off the cliff, you can see right through the grill of the truck (meaning there is no radiator or engine), and the transmission is also missing, as you can see when the truck is falling upside down. Without an engine or transmission it would be hard to drive off a cliff.
Revealing mistake: When Francis emerges from the cave, he stands in the foreground, with the distant mountains and sun in the background. The sun creates a lens flare, which is an internal reflection within the camera lens. Yet Francis is in front of the flare. This shows that the actor was composited with the background via a traveling matte process.
Revealing mistake: When Herbie is being pulled from the truck at Crazy Dave's, Herbie goes into reverse and the camera does a closeup shot of one of the rear wheels reversing. If you look carefully, you can see an extra set of small wheels behind the tyre which are obviously propping the car up enough so that the cars proper wheels will only skid and not get any traction.
Revealing mistake: When Stuart's dad is giving final instructions to Stuart as he's about to lower him down the drain, Stuart (and his bright yellow shirt) aren't reflected in the dad's glasses.
Revealing mistake: It is obvious a dummy was used when Steve is thrown from his easy chair into the kitchen cabinet.
Revealing mistake: After Draco flees the cave, Bowen is riding his horse in the water after him. You can easily see that it isn't Dennis Quaid but his stunt double.
Revealing mistake: Near the beginning when they are in the pool and the first earthquake hits. You can see a board covered in soil lift up, which the dog is on.
Revealing mistake: During the Hy Brasil sinking sequence you can see a horizontal line in the water in the background, this is the edge of the water tank they used to film this sequence. It's also visible in several shots from the longship.
Revealing mistake: When the genie (Burl Ives) moves the fire plug you can see a bracket holding it up and running down to a track beneath it.
Revealing mistake: Near the end when a naked John Jasper kills M, he staggers back and you can see a modesty pouch that is covering his private parts. (01:31:47)
Revealing mistake: When the eye is flying toward Bobby Jo, you can see the rig holding the eye as it flies and the wire when it enters her mouth. (00:41:45)
Revealing mistake: When Christina Ricci picks up the silver knife off the floor in her house and her hand starts to smoke, pay attention to the shadow. You can see smoke coming from her wrist before her hand touches the knife.
Revealing mistake: When the man shoots a target next to Jack's second cousin's head you can see a shot of him pointing his gun. It is clear there is a pole supporting the gun. (00:20:35)
Revealing mistake: When the bleached dead girl is lying on the table, you can see her breathing. (00:13:45)