The exterior location used for the "Winer" mansion is identical to the "Kendrick" mansion in The Adventure of the Lover's Leap (1975).
Lucie Arnaz appears at the 21 minute mark for about 30 seconds, doing a 'Jimmy Durante' impression and singing a song while Ellery looks on. The song is "I've Got to Tell you the Truth" - a Tin Pan Alley song.
Final appearance of Simon Brimmer.
Alvin Winer is portrayed as publicly beloved and admired but privately a martinet and a bully. Rudy Vallee, who plays Winer, was infamous for being difficult to work with (one of the series regulars on Batman (1966) described his three-episode guest appearance as "three weeks of hell").
Simon Brimmer (John Hillerman) ends the episode with a personal anecdote while the remaining characters leave. This would be a running gag for his character of Jonathan Higgins in Magnum P.I. (1980).