The Griswolds are watching the Keno numbers being called and their last two dollars slipping away. The camera shows the Keno board and the numbers already called. When number 80 is called, you can clearly see that number 30 is lit on the call board. Number 30 does not come out until one or two numbers after 80 is called. Also, notice the sequence of balls in the "call cylinder" are not in proper sequence either!