In the first sequence in which various newspaper headlines are shown, one story begins, "In a twist worthy of a Conan Doyle novella, Mr. Sherlock Holmes was yesterday revealed to be an expert witness at the trial of 'Jim' Moriarty."
The song that is used when Moriarty steals the crown jewels is 'La Gazza Ladra (The Thieving Magpie)' by Gioachino Rossini.
Ian Hallard, who plays Moriarty's defense attorney, is the real-life husband of Mark Gatiss, who plays Mycroft Holmes and who is also co-creator and writer of the show.
Douglas Wilmer, seen in the Diogenes Club, played Sherlock Holmes in Sherlock Holmes (1964) and Sherlock Holmes' cleverer Bruder (1975).
Moriarty keeps referencing his "Final Problem" - namely, how he and Sherlock will settle their score. This is a reference to the Sherlock Holmes story "The Final Problem," which was the basis for this episode.