1) When the guys are a at the checkout counter of the supermarket and about to steal all the meat under their shirt, they talk to the cashier, and her cash register is correct, but when it cuts back to him talking, the cash register behind him is an electronic one with digital output, which wasn't around at the time period (1969 or so) this movie was supposed to be in.

2) The car they take on the road trip wasn't created till about 8 years after the time (1969 or so) movie was supposed to take place.

I saw these slip-ups on TV, they were showing them before the commercial breaks, then I got the tape and looked and they were correct.