After Andy, Barney, and Opie swap Aunt Bee's bad-tasting homemade pickles with some better-tasting store-bought pickles, they put the home canning jars that now contain store pickles back into the Taylor's kitchen cabinet. Barney then leaves the kitchen with a valise full of the bad homemade pickles in the store-bought jars. In the next scene, Barney is outside of town giving the motorist from Portland a home canning jar of Aunt Bee's bad pickles as a Safe Driver Award. He should be handing out the store jars from the valise, not home canning jars.
Throughout this episode, Aunt Bee refers to making a batch of pickles as making 8 quarts.
She tells Andy and Barney that they're the lucky ones because she made a double batch - 16 jars.
All recipes for a batch of pickles are for 7 quarts, not 8, because 7 is the number of quart jars that will fit in the standard, blue enamel, water bath canner. This canner size has been the standard for at least the last half of the 20th century and probably even earlier.
A plausible reason: Even though Aunt Bea had only moved in with Andy in the past year she easily could have been entering pickles in the county fair for the past 10 years from the town she formally lived in.