Plot hole: When Schaeffer, McFee, and Fergie drive to the Lapp farm to kill John, the car stops on top of a hill. Then it reverses a bit to be out of sight from the farm. But then the formerly careful guys get out and walk down the open road, sporting their guns like in an Italo western.
Plot hole: The way John confronts Samuel with the first suspect (throwing and pressing the guy against the side window of the car Samuel sits in) is plain ridiculous and certainly not the practice of a good cop like John. Later they have a proper confrontation with six more suspects.