Paul Drake (William Hopper) jumps off the boat, into the water to rescue Sally Fenner from the dog swimming after her. Hopper was a Navy frogman during WWII.
James Nusser, who gives a very sober performance as the judge in his sole series appearance, later would appear in 80 episodes of Gunsmoke (1955) in the recurring role of Louie Pheeters, Dodge City's town drunk.
This episode is very similar to The Case of the Impetuous Imp (1965). They both have the same basic premise of a note in a bottle supposedly proving that someone was murdered instead of accidentally dying in a boating accident. Both were based on the same novel, Erle Stanley Gardner's "The Case of the Negligent Nymph".
Perry's boat is a Skagit. Most likely their 20 or 21 foot Express model equipped with a pair of Johnson SeaHorse 35 HP outboards.
The bottle Dorian found on the beach is a Lauders blended scotch whisky bottle.