Guest stars William Windom and Joe Maross also teamed up on the Season 2 episode The Widow (1967) as drug dealers.
Phelps poses as "hitman" Dave Ryker. In an earlier show titled "Boomerang", he was also a "hitman" named Dave Ryker.
Pete Novak's house with the steps that go over the hedge was also seen in Mannix.
In one scene, Mitchell tells his partner not to shoot Barney, saying "Jay. Jay." Or read another way as J.J. The partner's surname is Braddock. They're in the fight business. J.J. Braddock is The Cinderella Man (fighter) played by Russell Crowe, about the Depression-era fighter James J. Braddock.
The distinctive bass solo work is by jazz great Ray Brown.