The title references the English name for the notorious French prison located about 6 nautical miles off the coast of French Guiana. Operating from 1852 to 1953, the small island (35 acres) of Île du Diable was the home for 80,000 political and criminal prisoner's whom mostly were never heard of again.
This episode takes place on Devil's Island, French Guiana, South America on March 14, 1895 and in Arizona in 1968.
Theodore Marcuse, who plays Lescaux, had earlier guest starred in the similarly themed The Night of the Bottomless Pit (1966).
Oscar Beregi Jr. and Theodore Marcuse were both very busy actors during the 1960s, but this may be the only work they've done together. More likely, they were typically competing for the same roles. Unfortunately, both also died relatively young.
Oscar Beregi Jr. also played someone responsible for torturing and killing prisoners in The Twilight Zone (1959) Deaths-Head Revisited (1961).