Revealing mistake: When The Mask is dancing with Tina and he turns her into a human tornado while spinning her around, none of the onlookers in the crowd show the slightest bit of amazement at the impossible feat that just occurred in front of them, indicating that the extras were not directed to react to the special effects.
Revealing mistake: In the final game against Iceland scene, there is a point where you can see that the people in the stands are actually cardboard cut-outs.
Revealing mistake: When running towards the "bear attack", Sean activates the Guyver. Close ups of the armor attaching itself to his body show that's not really Sean as his arm and leg are both seen not moving even though he's running to where the attack is occurring.
Revealing mistake: Signs for Baltimore based businesses are clearly visible in the stands, such as "Sheraton Inner Harbour" and various Baltimore banks.
Revealing mistake: When the camera pans across Kareem Abdul Jabar's dead body sprawled out on the steps, the corpse blinks.
Revealing mistake: The Aspen lift operators are wearing Copper Mountain uniforms. Copper Mountain is in Colorado, but it is over two hours away from Aspen.
Revealing mistake: In the fight between Julie and Ned, when she does the last kick to take him down, it's obvious that she doesn't actually kick him.
Revealing mistake: During the scene where Arnold's character is escaping from the mansion at the beginning of the movie, there is a part where he is running down a snowy hill through trees. At one point during the hill scene, Arnold does a flip head first. When he lands the flip, you can clearly see the stunt double's face as he turns to shoot at more bad guys. (00:13:30)
Revealing mistake: When Alfalfa is running in the street only in his underwear and socks, it is very obvious that he has sneakers under his socks.
Revealing mistake: In the scene where O'Neil is fighting Ra's bodyguard, the bodyguard uses claws and hits O'Neil's back, tearing his shirt and wounding him. But you can see Kurt's "wounds" and torn shirt right before he's hit by the bodyguard (a scene after Ra's bodyguard's claws are shown). (01:49:10)