Continuity mistake: When the Terminator pulls John off the dirt bike during the drainage ditch chase, the dirt bike falls onto its left side and the gas tank is about to be crushed by the tow truck. The next shot from another angle shows the dirt bike laying on its right side, with the rear tire the first thing to be crushed under the truck. (00:37:30)
Revealing mistake: There's one scene where they are surrounded by the foot. Leonardo reaches behind him for his katanas, but he doesn't unsheath them. If you look at his elbows, you can see gaps in the pads where the actor in the suit hasn't fully fastened the gloves to the rest of the outfit. (01:05:40)
Revealing mistake: When Charlie shoots the critter which flies into the air and explodes, we can see the wire the critter is attached to. (01:07:45)
Plot hole: The assassin cuts a hole in the glass to kill the Federation president. But with the size of the hole and the placement of the scope on the phaser rifle, the assassin would not have been able to see out of the hole.
Revealing mistake: When Bill and Ted leave the house with their "bad" selves, Keanu Reeves' double is seen as they move past the camera. (00:21:20)