When Andy comes into the store at night and finds Barney and Ben Weaver, he reaches for the light switch and the lights come on, even though he obviously does not move the switch. Moments later, the switch is still in the same "off" position it was before the lights came on.
Ben Weaver tells Barney to put down the umbrella bottle opener or pay $1.25. There is no need for Barney to do this, as he hasn't left the store with the item.
At the beginning of the episode, when Andy and Barney are sitting in the patrol car, at the very top of the screen a hole is visible in the roof of the car, directly over Andy and Barney's heads. This was likely done to create better lighting for the interior shots of the car.
When Andy and Barney are in the office before Barney goes undercover, Andy looks up and to the right, behind him, then announces that the store opens in 15 minutes. The wider shot shows that there isn't a clock there.