This episode, "A Black Day for Mayberry," features performances by three members of the Howard family: Ron Howard in his regular role as Opie, Clint Howard in his recurring role as Leon and their father, Rance Howard, as a government agent.
In the opening scene, the two Treasury Agents are indifferent to Barney and are waiting in the courthouse for the Sheriff to return. Barney is agitated at being dismissed by them. He picks up the phone book from the Sheriff's desk and begins to nervously flip through it. In several screen shots of Barney holding the phone book, "Mount Airy," Andy Griffith's birthplace and hometown, is printed on the cover. It has been a long held belief that the fictional town of Mayberry is based on Mount Airy, North Carolina. EDIT: It is a misconception that Mayberry is based on Mount Airy, NC. Andy Griffith explained in an interview that "Mayberry" is actually based on Pilot Mountain, NC (a much smaller town than Mount Airy) and "Mount Pilot" is based on Mount Airy (a much larger town than Pilot Mountain).
This is the first episode in which the third and final location for Wally's Filling Station is used.
Andy Griffith's hometown is Mount Airy, NC. Fort Knox plays a central role in this episode and the granite used to construct Fort Knox came from a quarry in Mount Airy.
Deputy Gomer Pyle (Jim Nabors) carries a protest sign for Regis (Doodles Weaver) which reads, "Down with the Gold Standard! Vote for the Single Tax!" At the time this episode aired, two weeks before his assassination, one of the issues facing President John F. Kennedy focused on whether or not the United States should return to the gold standard or continue to make silver-backed currency and fiat currency without tangible subsidy. On March 20, 1968, Congress repealed the requirement for a gold reserve to back U.S. currency.