The taxi cab that Linkletter's character gets into at the Trailways station is not the one he later gets out of near campus. The second one has a different unit number, a No Smoking sign, and a missing whitewall tire.
When the GTO guy arrives he places a few aluminum drink cans on the ground and they clearly sound empty. When he and Nova pick up the Hitchhiker Awaiting 'True Call', they give him one of the cans which is now full.
When Happy-Go-Lucky Guy presses the button to get his change back from the newspaper machine, you clearly see and hear the change falling into the return slot. When he checks to see if it has fallen, he doesn't find anything.