After more than four seasons of seeing Perry, Paul Drake, and various clients and suspects driving around in random cars (Buicks, Cadillacs, Chevys, etc.), this was the first episode to feature the credit in the end titles: "Automobiles Supplied by Ford Motor Company". From here on out, everyone on the show would be seen driving Ford Galaxies, Falcons, Thunderbirds, Lincoln Continentals, and the like.
Because one of the central elements of this storyline is a jazz ensemble featuring guest star James Drury on piano, the entire musical score (with the exception of the opening and end titles) is jazzier than usual, heavily featuring bongos, horn riffs and quick staccato strings.
Amongst the many snippets of music being played, one is a jazzy version of The Perry Mason Theme.
In something of a mystery within the mystery, when Perry is in Bongo's room, he plays a tape that contains the song "A Walk in the Black Forest". But according to all resources, the song was written four years later, in 1965, by Horst Jankowski, whose recording shot to No. 1 on the easy listening charts in the U.S. and No. 12 on the Billboard Hot 100. According to the Forgotten Hits blog, Jankowski wrote the song in 1961 for a German radio show that focused on travel. He was paid 125 Deutsch Marks (about $600 at the time) for the song and didn't regain the rights to the song until seven years later, so he didn't make a dime from royalties when it was a hit. In the meantime, the song popped up on two other Perry Mason episodes - The Case of the Absent Artist (1962) and The Case of the Potted Planter (1963) - and Cavender Is Coming (1962), starring Carol Burnett.