Gene Lyons, who plays Ralph Balfour, would later appear with Raymond Burr on Burr's series Ironside (1967) in the role of San Francisco police commissioner Dennis Randall.
Marian McCargo, who played Louise Selff, is the mother of William R. Moses, who was Ken Malansky in the later Perry Mason TV movies.
The large portrait in this episode was previously seen in The Case of the Thermal Thief (1965). The same actor (John Hart) is represented in both portraits, and he did indeed appear in the previous episode ("Thermal Thief") as well as this one. In "Thermal Thief," the portrait is of "Dion;" In this episode, he is "Jamison."
Characters with the last name Balfour also appeared in two other episodes in the series: The Case of the Lucky Loser (1958) and The Case of the Devious Delinquent (1963).