This episode served as a pilot for a spin-off series starring Erin Gray, but a series was not ordered.
Lisa is played by Jacquelyn Ray, who was Tom Selleck's wife at the time this episode was done.
This is the most notable of several episodes that contradicts the theory that Robin Masters may be none other than Higgins himself. (NOTE: The Higgins-might-be-Masters was just a running joke in the last season. It wasn't meant to be taken seriously.)
Part of the history of the Haiku Stairs are true. It was a low frequency radio antenna and radio station build during WWII. The Haiku Radio Station was commissioned by the USN after the bombing of Pearl Harbor on Dec 7, 1941. The proposal was approved in 1942.
This is the first episode where T.C. calls Higgins "Higgie Baby".