Van Johnson tried to cope with his movie career hitting the skids by creating a singing nightclub act. This episode was clearly written so as to promote his singing, which gets tiresome and embarrassing quickly. Also, the director used his little minstrel tune as the instrumental cue for Johnson, so that by the time you are done, you have this awful song virus, even worse than the Verve's dreadful 1990's pop song 'Bittersweet Sympony.'
Johnson was getting soft and jowly by the 1960's, so he is, in general an unimpressive villain anyway, even without the singing. He and Alan (Alfred) Napier had worked together in '30 Seconds Over Tokyo,' Johnson's best movie, so maybe they had a drink together after shooting this episode, or maybe not. Regardless, this show was another step on the long way down from being an A-lister in the mid-1940's. By the late 1970's, Johnson would be shucking Poly-Grip and appearing on The Love Boat.
The death trap, slow roasting of the Dynamic Duo, is in worse taste than usual, and their escape is unimpressive. The high point for the whole episode is a cameo by Phyllis Diller. I recommend skipping this one.