Continuity mistake: McCaleb sees the suspect parked across the street in a car, he then takes the shotgun from the trunk of his car. Detective Winston then exits the car and is seen at the rear of the car saying "You're killing me here, what's going on?". McCaleb then shoots up the suspects car. At the end of the scene Detective Winston is then seen getting out of the car for a second time, despite the fact that she has already got out of it once already. (01:14:00 - 01:15:20)
Continuity mistake: When Terry is back outside at the store he glances across the street and sees the same car. Notice the angle of the tires, they are turned. In the next shot the tyres are straight. The car has not even moved yet. (01:14:19)
Continuity mistake: In one of the final scenes, Eastwood's boat is shown underway in perfect condition after De Jesus rams its bow into the grounded freighter.
Continuity mistake: When Eastwood and De Jesus are walking near the water, De Jesus remarks "What a great sunset" with the sun right on the horizon, then a shot of her nephew with a shadow far too short to be anywhere near sunset.
Plot hole: Clint Eastwood's whole investigation/solution is based on him suspecting that the victims had a common tie, rather than being random. The problem is there is no reason for him to think this - there is no reason given for them to not be considered random victims. For him to think otherwise was a bit far fetched. In the book, however, they were all on the organ donor list, which led him to the fact they all had the same rare blood type and so on.
Factual error: In the scene where, Clint is examining his scar, the scar is misplaced. It should run from the top of the sternum between the collar bones to the bottom of sternum, mid diaphragm.