Stonewall's sunglasses disappear and reappear between shots when Thunderhead signs up to join the force.
The position of Stonewall's bike in the pond after he falls off it during motorcycle training.
Almost all of Herb's lines are obviously overdubbed and done so in a fairly standard North American accent (he's the drunken cop). But in a scene that does not appear to overdubbed, he says "it wasn't our fault someone took a shot at the governor" in a British accent.
When the gang members chase after Clint in the diner, the actors almost stop running when they reach the back exit.
Visible when Mike and Winston pull over a red car by a corn field.
Visible when Gorman is chastising his fellow recruits for turning down the mayor's offer.