When Skip and Ronny are checking in the hotel, a woman can be seen walking behind them, but in the next shot, she is still walking, but even more behind them.
The position of the girl electrocuted on the motorcycle when she falls
to the ground doesn't match the one when she is shown from up close.
Around 52' in, Gail finishes a shift at the bar and has already begun to remove her apron to pass to her replacement before she even sees that the replacement has arrived.
Ronny is clearly moving his eyes in the shot where the policemen are looking at him when he is dead.
Despite the obvious size and power of the biker's ride, the speedometer only goes up to 80mph. Presumably even doing 100mph looks less impressive if the machine is capable of 150+.
When Skip and Gale are communicating through radio, Skip's mouth doesn't move when he says "What?"
After another fake death hoax on the beach, the girl goes back to her RV to change clothes. At the end of that shot, you can see someone's (leg/boot showing) sitting at the table.
How does the motorcycle killer ever come to know about the secretive prostitute working at the hotel? He has never previously visited this location, or been aware of her deception. Nor has he even met the woman in his civilian identity.