When Jones asks about the book he's reading, Smith tells him it's Life on the Mississippi (published in 1883) by Mark Twain. Jones says that name is obviously an alias, which it was, for Samuel Langhorne Clemens. The pen name comes from the term used on riverboats, to indicate that the channel depth is deep enough to allow a boat's passage without grounding.
The performance of guest star Noah Beery Jr.was so well-received, that when Roy Huggins was looking for an actor to play Jim Rockfor's father, Rocky, in the classic series, The Rockford Files (1974). When the series went into production, Noah was cast (Robert Donley was only in the series' pilot).
The ranch house where Hank and Sarah Henderson live is the same house used for the home of Judge Garth in The Virginian (1962). That show had just finished its nine season run the previous season.
The title as used here implies a crime so serious it would result in death by hanging. It was apparently coined by John Lennon for The Beatles' song "Strawberry Fields Forever". The meaning of the phrase in that song is not clear, but given that the song is largely meaningless, it may just be part of a stream-of-consciousness kind of writing.