At 20:03, Daphne tickles Mr. Shwamp's chin as she dances with Andy. Barney and Skippy also dance past Mr. Shwamp. The next cut shows Thelma Lou, Helen, Gomer, and Goober's table. Mr. Shwamp is immediately seen sitting behind them.
It's never explained why Barney has to take the car to get food rather than walk, as had been done previously in this small town.
After communicating that Andy and Barney will not be going to the movies with Helen and Thelma Lou, Andy opens the door to let them out. You can see a building with a window across the street. He immediately reopens the door, but the view of the building is blocked by what looks to be a wall. There appears to be no break in the scene, so this is quite mysterious.
As Helen and Thelma Lou exit the theater, the movie poster behind them says "Gary" Grant instead of "Cary" Grant.
While taking inventory, Barney mentions his low "sugar blood" rather than blood sugar.