The Playland Arcade scenes were filmed at the Santa Monica, California Looff Hippodrome. This location also was used as the carousel where Henry Gondorff (Paul Newman's character in The Sting (1973)) lived and worked. In The Sting, the carousel was located in Chicago.
The old boarded-up house where Columbo meets Kate Freestone is the same "post-disaster" house set used in Earthquake (1974).
In conversation with Walter in the projection room, Columbo asks Walter for permission to take one of the editor's cotton gloves for his 15-year-old nephew who makes 8mm movies. He adds that when he was a kid in his neighborhood, they had heroes like Joe DiMaggio and Phil Rizutto, but his nephew has Francis Ford Coppola on his wall. In real life, Falk and Coppola knew each other. Some years earlier, Peter Falk had approached director Coppola to ask about playing the part of the consigliere, Tom Hagen, in The Godfather (1972). The role went to Robert Duvall. Coppola's handwritten casting notes reveal that he also considered casting Falk in the role of Sonny before deciding on James Caan.
When Columbo is alone in the television control booth, he whistles a few bars of This Old Man, something he did often enough that it became sort of a theme tune for him.
An extremely rare episode since Columbo appears before (at the opening credits) and during the murder instead of only showing up afterwards.