Right side headlamp on George Ryan's car during the chase scene keeps varying from damaged to undamaged.
The entire basis of the film is that slot machines are programmed to pay off at certain times. They are actually programmed to pay off a fixed percentage of their take at random times.
Slot machine rip-off scheme involves sending radio messages to a player who races from casino to casino to cash in on machines that are just about to pay off - but doesn't take into account that in many cases it would take up to a half hour to get from one casino to the next.