The Chevelles are switched numerous times. One has damage and one not so much, but it is made most obvious by the 2 different rim types. One is with holes and the other solids.
When one of the robber shot the boatman when he was going to call Sheriff on radio, his mouthpiece radio transmitter also fell in the water with him in his hand. But when all the robbers gathered there they found it on the ground and dry.
Before Nate's ring finger is amputated, you can briefly see that his pinky has already been severed. But there was only one amputation.
When Shane (Nate's son) confronts the boatman about the missing money, Nate intervenes. In the first shot, he has blood all over the left side of his face. However, in the remaining scenes, the blood is no longer there.
The ring finger of Nate's left hand is supposedly severed, but if you look closely it's his right ring finger that is amputated. But when he stands up, he is grabbing his left hand.
4 million dollars in $100 bills is about 40 kg (88 lbs), the bag with money is handled and thrown around like it weighs a fraction of that.
After the family crash the Land Rover, their pursuers arrive on scene from the same direction that the family exited while fleeing. Logically, they should have been following the vehicle, not in-front of it.