Revealing mistake: Doug has the hologram when inside the alien nuclear reactor, and a bunch of bad guys encircle the holographic image and fire at it at point blank with automatic weapons, and not one bad guy gets hit. If they encircled the 3D image, at least a few bad guys would have been hit by their own men. (01:37:00)
Revealing mistake: In the extended version of the film during the buffalo hunt, there is a shot of a buffalo making a turn and in the distant horizon, you can briefly see a modern radio tower on top of a hill.
Revealing mistake: At the end, when the train destroys the time machine, right at the moment when it hits you can see a small explosion, which was used to trigger the destruction of the time machine. (01:43:03)
Revealing mistake: When Danny falls down from the ceiling, watch closely and you can see the security wire attached to his leg. (00:34:40)
Revealing mistake: In the scene where Jack Ryan is brought aboard the U.S.S. Dallas after releasing himself from the helicopter, two crewmen drag him inside. The crewman on the left side of the passage backs into a metal valve, but the valve moves down and left, then snaps back in place as if mounted to a rubber pipe.
Revealing mistake: When Marsten's men are forcing Aborigines off a cliff, Quigley shoots one man who falls over the edge with his horse. Just as the horse and rider fall over, you can briefly see the rigging used to flip the mechanical horse over the edge.
Revealing mistake: When we see the navy seals burst into the factory to rescue the pilots, several of the bad guys get shot. On one of the bad guy's feet who falls back onto a table, there is a rope attached to his foot obviously so he wouldn't fall to far, or not to hurt himself or something. (00:09:50)
Revealing mistake: Every time there is a wide shot of the dragon flying it never flaps its wings. But when there is a close up, it is flapping its wings. (00:28:10)
Revealing mistake: When "Krebbs" the koala is discussing with his other friends in the cell. If you look closely, you can notice a blink in the outline in the "Krebbs" nose. It's a clear ink & paint mistake of the blur line.
Revealing mistake: A shot of Mel and Goldie on the motorcycle in Michigan is re-used for a shot when they are supposedly in Wisconsin. They are driving along a curving, downsloping road.
Revealing mistake: When the boys use the glasses to start the fire, there is smoke coming from under the wood they are lighting. This wouldn't happen. It would come only from the focused point of light made by the glasses.
Revealing mistake: When Webby and the others are standing outside of the window watching Scrooge pace back and forth in anger, she casts no shadow on the patio. This is revealed when she moves left at one point. (00:28:50)