During the sequence where Crockett goes out on his motorboat to think things over, the sun keeps moving up and down as the camera cuts back and forth between the flashbacks and Crockett on his boat.
When the punks break into the side window of the car they are going to steal, the glass is clearly not safety glass.
During the scene where Sonny and Brenda take the yacht out, you can see the wake from the other boat the camera is on.
During the first chase scene with the punks and the driver of the yellow truck, you can see the crew visible in the back of the pickup truck via reflection off of the "punks'" car.