Other mistake: The reporting of the horse race used to sting Doyle Lonnegan stops as soon as the fake FBI agents raid the bookmakers. J J Singleton, who is reading the results of the race, stops when he sees the raid taking place. However, that was supposed to be a live broadcast from the racetrack itself. It should have continued. Lonnegan isn't stupid - he would pick up on something like that immediately.
Other mistake: Why is the cashier sitting behind bars in the mock-up bookies when he just steps out of the side to go and fetch Gondorf? If anyone wanted to get at the cashiers they could just walk around the side where there is no door.
Suggested correction: It's partly psychological. Also, anyone going around the bars would be slowed down, more than simply reaching over, giving the cashier the opportunity to react.
Other mistake: Wrecking Crew was 3-1. Ray Walston announces he paid $6.00 to win. If he was 3-1, he would have paid $8.00.
Suggested correction: This isn't a mistake. The person "operating the radio" could easily have switched it off because of the commotion. Lonnegan would simply suppose this is what had happened. He is not going to instantly suspect someone is faking the whole thing.