Continuity mistake: After Ellis and his mom are stopped by the Troopers, one of them holds a clip board with Mud's picture on it and finger prints. As he is showing it to Ellis, the close up shows his fingers over the finger prints as he is holding it one-handed. Then in a further shot, his fingers are suddenly holding the board about 2 inches above the finger prints.
Continuity mistake: Once Mud reveals who he shot and asks for Neckbone and Ellis to help him get the boat out of the tree, Neck asks for the pistol in return. Mud reaches around his back and puts his hand on the handle of the pistol tucked in the back of his jeans as he begins saying his shirt and pistol are the only things of value he has. It cuts to a close up, and suddenly his hand is on his hip and he reaches for his shirt, then back around to his pistol again.