Revealing mistake: In the scene at the Pope's apartment, when Clouseau enters the balcony for the second time to "look at the moon", there is a third shot from his back when he is leaning out of the balcony. You can see a platform which supposedly was there to help him easily fall out. (00:54:35)
Revealing mistake: When Larry floats drowned in the pool, his face remains motionless until the very last second, when he starts to chuckle: probably a flaw of the actor straining for the last bit of air.
Revealing mistake: When the girl is giving the guy a blow job in the school restroom, he finishes in her mouth. She goes to the sink and spits it out. You can obviously tell she had a mouthful of water going by the color and quantity. (00:20:45)
Revealing mistake: When Georgia and Poupi are walking back towards the bus from the store where she buys food for everyone, several bystanders at both sides of the road just stand there looking at the camera. (00:17:30)
Revealing mistake: When they drive out of Vegas, headed for Witch Mountain, there is a shot that appears to be made with a camera on a mobile cherry picker. The camera sweeps across the road and up high, watching as the vehicle passes under the camera. As it passes the camera, you can see a trail of dust that was kicked up by the cherry picker. It crosses the road and is still floating in the air from a recent crossing.
Revealing mistake: When Needy uses her key to unlock the door, you can see the door is already open. (00:58:07)