The Père Malfait was played by Richard Kiel, who also played the Diablero the previous week in "Bad Medicine." Producers liked him so much in both roles, they asked him to be available for a second season of the show. When ABC flip-flopped on whether to renew the show, Kiel opted for a role on the short-lived Barbary Coast (1975) instead.
Though Donald Mantooth is credited only as "Sleep Subject," his character is named numerous times in dialogue as "Paul Langois."
Kolchak comments that the total value of Chez Voltaire's wine cellar exceeded the gross national product of Paraguay. In 1974, Paraguay's GNP was approximately $1.185 Billion dollars.
Kolchak mispronounces the word bayou as "bay-yew" which may have been done deliberately to show his ignorance of Louisiana. While most people pronounce it as "bye-yew", it is correctly pronounced as "bye-oh".
When Kolchak goes looking for Morris, it's the same staircase where he finds "The Monk".