Other mistake: While Sam is working in the yard, Goober drives up and hands Sam a registered letter from New York City. The post office had called Sam to tell him Goober was bringing the letter. However, a registered letter has to be signed for by the addressee. (The delivery receipt is form #3849.) Goober would not have been allowed to sign for it.
Factual error: Howard and Emmett travel to New York City to take part in a televised panel discussion on the merits of city life versus small-town life. The station is "KZOK Channel 12." All television stations east of the Mississippi River begin with the letter W, not K.