Michele Hicks makes an appearance in this episode. She was the wife of Jonny Lee Miller, who plays Sherlock Holmes, at the time of the episode.
The title of the episode is a reference to "The Disappearance of Lady Frances Carfax" an original Sherlock Holmes story.
Herman Wolf, a retired music promoter introduced early in the episode, is played by Marvin "Meat Loaf" Aday. In addition to his long acting career (The Rocky Horror Picture Show, Wayne's World, Crazy in Alabama, Fight Club, etc.), Meat Loaf is perhaps better known as a recording artist. His hit songs include "Two Out of Three Ain't Bad," "Paradise by the Dashboard Light," and "I'd Do Anything for Love (But I Won't Do That)."
The actress who plays Emily Gray was cast 11 years prior in the unaired pilot for The Big Bang Theory. Her character, who had some characteristics of Sheldon's later girlfriend, Amy, was written-out for the successful pilot.