Factual error: When Preach hears Cochise is in trouble, he is shown running down a street looking for him. In the driveway of one of the houses is a maroon 1973 Chevrolet Monte Carlo, but the movie takes place in 1965. (01:03:15)
Continuity mistake: Pooter's hair was cut in the scene where they sneaked out of class to go to the zoo, but when they got to the zoo his hair was grown out.
Factual error: In the opening scene, the guys hop a ride on the back of a CTA bus. That bus was a darker green with windows that would open and was true to the time period of the sixties A lighter lime green bus passed them from across the street. That bus had windows that did not open, because that's when the CTA introduced air-conditioned buses. Those buses rolled out in the early seventies, much later than the time period portrayed in the movie.
Continuity mistake: When Preacher throws the dice for 50 cents, he's seen in the middle of his two opponents throwing the dice, but when the camera angle changes after he throws them, he is now seen to the left of them.
Answer: Maybe the people in the car saw Cochise's letterman jacket and recognized the school.