Continuity mistake: When Jr. is driving with his family in the car, you can see a car behind them. Not only does the care stay the same length behind them as he speeds up to 100 mph, but when he pulls over and puts the gun on his wife, you never see the car pass him. It may have passed when the camera was on the wife, but then we should have heard it (the window was down: we know that 'cause he threw his kid's shoe out). Yet when he pulls back onto the road, the car is not behind him.
Continuity mistake: After Junior swerves onto a side road because his wife lunges between him and the steering wheel, a distant shot shows him still swerving, but for no apparent reason since she is no longer there.
Continuity mistake: When Junior is driving in the car with his family and says he is going to kill them all driving really fast, he cranks the steering wheel as far as it will go, but then the next scene shows the car still going straight with just a little bit a swerving.