Despite Larry Grundy working with Archie at the plant and living across the street, this is the only episode we ever see Grundy or even hear his name mentioned.
The newspaper Archie is reading at the end is the September 21, 1971 edition of the New York Daily News.
When the investigating agent shows up at the Bunkers' house, Archie lets the agent sit in his chair, something he almost never does.
The initials in the title are an abbreviation for the Federal Bureau of Investigation, a Department of Justice agency that serves as a federal criminal investigative body and was founded in 1932, though special federal investigations occurred prior to this date. Its motto is "Fidelity, Bravery, Integrity" (F.B.I.) and its most famous director was J. Edgar Hoover, who served from 1924-72.