Revealing mistake: Utility poles are visible in the scene of the Japanese aircraft carrier launching planes for the first attack on Midway.
Revealing mistake: Rocky says "cut my eye" during the fight scene, if you watch closly you can see the man actually squeeze a tube full of red stuff inches away from his eye. It's really quite funny... (01:49:20)
Revealing mistake: When Kong first shows up to take Dwan away, he roars and pounds his chest. As he does so, the breastplate in Rick Baker's costume vibrates visibly in a way that a flesh-and-blood chest wouldn't.
Revealing mistake: Navarro is climbing on the outside of the train, the overhead shot shows very wide gaps between the plates welded to the windows. When the shot changes to a side-on view, the gaps are considerably smaller. This is seen several times throughout the quick scene changes. (01:47:00 - 01:49:30)
Revealing mistake: When the armed gang abduct the Mayor, a LAW rocket is fired at a Lorry, the few seconds are obviously several shots pieced together. The giveaway being the driver is a dummy as the driver has no face, even after the explosion, the faceless dummy just falls out of the cab.
Revealing mistake: In the aerial shot where the Pantera explodes on the highway, you can see that it's a crude mock-up on some type of rolling trailer. Also, it appears to only be moving at 30 or 40 mph, which is WAY slower than the 160 mph speed indicated in the movie.
Revealing mistake: Following their escape from the comancheros, the two wheeled wagon driven by the old woman had a set of reins coming through the slats beneath the seat indicating that the old lady held fake reins and the wagon/horses were controlled by someone inside. Later, when they left the small town and headed to her son's ranch, a little window had been cut out of the slats where the control reins came through, no doubt to improve visibility and horse control.
Revealing mistake: When Scotty tells Dan to test the bus' aerodynamics, the bus passes the same scenery multiple times.
Revealing mistake: By order of the shrewd Harry Webb, the helicopter just destroyed the Cessna on the ground. The two guys decide that they are gonna walk back to civilization. Cut to the vehicle driving to the explosion site, and you can see in the desert sand ahead of the jeep fresh tire tracks from previous takes. And it keeps happening during the desert chase. (00:10:20)