I agree completely Anonymou,
The business is that of the OWNER'S, not the employees. If the owner decides to play his luck with the time that is his business and he'll eventually be caught. However, being a regional supervisor and owning a drive-in myself, the closing early part is at the mercy of the OWNER. I have fired a few assistants for running the store as though it was their own and closing early. This type of behavior is strictly prohibited!
Also, employees are not allowed to stay over their allotted time in my drive-ins either. I consider that to be mooching hours. You work what you are supposed to work. You don't have your go-home work done before it's time to go? You still leave and get written up for it. Managers have the responsibility of keeping their labor hours in check which is what these owners are doing.
If you feel you have an unfair labor case or feel that you can prove that he is breaking the law by tampering with time sheets, then take it to the labor board in your state. They'll investigate the case if you have proof. Otherwise, live with it.
Lastly, it is strictly against operational procedures to have off the clock employees or the public present in your drive-in at ANY time- Open, Close, or Mid-Shift. So, if you are off the clock- STAY OUT!