Continuity mistake: Abel Turner at the beginning of the movie is having a discipline-filled breakfast with his kids. Marcus arrives at the table and his glass of orange juice is full practically to the brim. In any other angle, the level of liquid is lower. (00:03:00)
Continuity mistake: Lisa is in the pool and kisses Chris who just had a chat with the creepy Abel Turner. She has her hands on the edge of the pool when the kiss begins, but at the cut her hands are underwater and Chris' fingers reach around the edge. (00:18:40)
Continuity mistake: In the scene in which Abel is facing the gunmen with the shotgun, after Abel takes the gun away from the gunman and holds it up under his chin, the view changes from Abel's face to the gunman's face. When Abel's face is shown, the gunman's face is low, but when it switches to the gunman's face, you can note that his head is tilted up higher, and vice versa.
Answer: He already had a much bigger mental problem in general, and not just about his wife or with Chris and Lisa. They were merely one of many triggers that could set him off.
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