Shirley Rogers who plays Denise is the same actress who appears in the well-known scene in the opening credits where she is being taught to snorkel while Magnum holds her.
In the scene when Stewart threatens Magnum with a large hook and demands that Magnum give him the keys to the boat, there was supposed to be a fight between the two characters. Selleck objected to the logic of that, and instead, proposed another option: Magnum and Amy/Carol jump overboard.
Mercedes McCambridge is well known for providing the voice of the demon in "The Exorcist." She also played Tom Selleck's mother in "The Sacketts."
Tom Selleck and guest star Ted Danson would work together again years later in the film "Three Men and a Baby" (1987) as well as its 1990 sequel.
Andrea Marcovicci's first appearance in the series. She later appears as Kendall Chase in Season 2 "The Sixth Position" (1981).