This was the first episode broadcast in color.
The horned idol is a prop from the movie "Atlantis, The Lost Continent"
One of the characters is a teacher named "Mr. Kavon." This is probably an in-joke, because there was a popular TV show at the time called Mr. Novak (1963) (Kavon spelled backwards), which was about a teacher.
When Solo introduces himself to Mrs. Alexander he says he's from UNCLE, and she says it's one of her favorite charities This was another inside joke about UNCLE not being connected to the U.N.
The statue of a pagan deity festooned with snakes used by Alexander for destroying his divorce settlement was originally made for use in the 1956 Biblical epic "The Prodigal", as a "statue of Baal".