Twice they are soaked to the skin in water and mud, but come up with dry cigarettes and matches.
The dirt on the shirts throughout the film goes from clean to dirty to clean and dirty. So does the dirt on the faces.
When Joker and Noah are tied to a post back-to-back, the position of the rope changes between shots.
Near the end of the film after Jackson falls into the mud trying to catch up to Cullen, there is thick mud all the way up his front over his shoulders. In the next shot his right shoulder is suddenly unmuddied.
After emergency personnel are on the scene of the accident, a siren is blaring as two men maneuver a gurney around the front fender of a Cadillac ambulance, but when the shot cuts closer, the ambulance has rather magically become a Ford.
The brush strokes in the tropical island painting on Billy and his mom's mantel are too subtle and delicate to be done with Paint-By-Number.
When Joker and Cullen arrive at the mud pit, their shirts are only partially wet, though they've been in the rain for some time.
The truck that was shown being recovered after crashing through a guard rail and rolling onto its top has no damage to the front or top of the cab, and the passenger side of the truck that would have hit the guard rail, and landed first when it rolled; has no damage at all. The only damage portrayed was to the wood side rails, a relatively inexpensive way to make the truck look damaged for a quick take.
When jumping into the mud pit, Tony Curtis' stunt double has a noticeable bald spot.
Within seconds of the first cut to the two men trying to wade across the river rapids, the first boulder that Cullen (Poitier) reaches for visibly moves when he touches it.
Whenever their hands and the chains/cuffs are shown close-up, what looks like a foam lining is visible. Real cuffs would not have comfort lining.
As John and Noah are swept downriver together, a person is seen on the shore moving into the top of frame, watching the two men.
When Joker and Cullen are cooking the frog, they are drying their cigarettes and matches by the fire--so how did they build that fire?