Plot hole: WARNING-SPOILER! Right after the climax, the paramedics show up to take Vince Vaughn away for being electrocuted and Teri Polo for being thrown against a wall and miscarrying her pregnancy. John Travolta has just been belted over the head with something at his boathouse and left for dead. Then he has the fight with Vince Vaughn where he gets belted in the head again with a paint can, gets kicked while he's down - then gets his head smashed through the passenger window of the SUV! And yet he is fine to drive off happily ever after - no medical attention required whatsoever.
Plot hole: When the police bring the car in for a forensic search after the murder, you see the policeman open the passenger door and he is correctly wearing rubber gloves. However, the policeman driving the car into the garage is not. Surely he should also be wearing gloves and not adding his finger prints all over the car?
Plot hole: The police don't find any trace of Ray's blood in Frank's car, after Ray was stabbed in the car.
Plot hole: In the middle of the film, after the custody hearing, Frank shows up at an event. Danny pretends that Frank dropped his wallet in order to have a brief conversation with his dad. Later, Rick confronts him about what they talked about. What does Rick expect? It's not like Danny will never be allowed to visit his father again. They are going to talk at some point. For Vince to expect that he will never talk to his father again is unrealistic.
Plot hole: After the boathouse incident, Frank tries to call and warn his family about Rick. Rick sees Frank's name on the caller ID, indicating his attempt on Frank's life was unsuccessful. Rick then goes into the garage and pulls Susan from the car, stating he just wants to keep Danny as collateral until he is safely out of town. Danny manages to escape. Rick chases the boy. Why? What's the point? All Rick had to do was get in the car and leave. Besides, one would think, taking Danny hostage would only make Frank and the police pursue him more.