Plot hole: Just before the final court appearance, detective Nunelly has the bullets in the evidence room swapped to match a planted gun in the shed under the lawn mower at Ted's house. At the end of the movie, Willie says that since Ted has killed his wife by removing life support he can now access the bullet in her brain and it will match the detectives' gun. So now he can prosecute him for murder, but there is a problem. It won't match because the bullets were swapped by the detective's friend who works in the evidence room.
Continuity mistake: In the end of the film where Willy and Ted stand together in Ted's house, Ted says to Willy "See, you can't touch me, ever". The shot goes to Willy and you can see his finger off the trigger, yet in the close-up on the trigger you can see that Willy's finger is inside the trigger-guard and he pulls it out.