Gomer and Thelma Lou's road trip scene starts by showing the truck from the rear, going down the road. It has a small rear window and nothing in the truck bed. The front-view shot of them talking inside the cab shows the truck as having a full-size rear window, with the rear covered by what looks like a tarp.
When Gomer tells Barney he'll drive Thelma Lou to her dental appointment, the window blinds are open behind Andy's desk. Backdrop scenery was missing and the elaborate Spanish-style homes stacked on the Hollywood Hills are visible in the "Mayberry" background.