Revealing mistake: In the scene at the end of the very first battle, where Imperial troops have just taken control of Princess Leia's rebel ship, Darth Vader breaks the neck of the Captain Antilles and tosses his body to the wall. The "dead" Captain puts up both of his hands to avoid slamming his face into the wall. (00:05:40)
Revealing mistake: At one point in the movie, dumptrucks are sent in to contain the Mighty Peking Man. You can tell that these, like most of the movie are toys.
Revealing mistake: When the UN team arrives in the Gobi desert, there's one shot where the helicopters and trucks are parked. They're supposed to be moving, but you can tell from the way the flags are moving that the wind is only coming from the helicopters.
Revealing mistake: Just after the helicopters crash during the chase with the crop duster keep a close eye and one of the helos is still in the shots flying.
Revealing mistake: The supposed deceased dog is breathing as Rack and spider lady examine him.