Joseph Campanella (Dr. Graham Aspinall) previously played Joe Mannix's boss, Lew Wickersham, throughout the first season of the series.
Guest star Burgess Meredith (Mr. Otway) was at the time of broadcast already starring as V.C.R. Cameron in the short-lived series Search (1972).
When Mannix goes in search of Burgess Meredith's incriminating evidence, that's recorded on a tape cartridge, his search takes him to a building's basement. As he works his way down the stairwell of the building notice on the walls a placard announcing the the building as a "Fall-Out" shelter. During the Cold War, many countries built fallout shelters for high-ranking government officials and crucial military facilities, such as Project Greek Island and the Cheyenne Mountain nuclear bunker in the United States and Canada's Emergency Government Headquarters. Plans were made, however, to use existing buildings with sturdy below-ground-level basements as makeshift fallout shelters. These buildings were placarded with the orange-yellow and black trefoil sign designed by United States Army Corps of Engineers director of administrative logistics support function Robert W. Blakeley in 1961.