Sorry for the delay on these — things have been crazy in my life, but when I had an unexpected snow day at work, I was able to catch up on my Elementary watching. Sadly, there aren’t many canon references in the past two episodes, but there are a few to point out.
Episode 212: The Diabolical Kind
Moriarty: Naturally, the biggest canon reference is to Moriarty herself. I’ve already touched on her previously, but I’m in love with this character.
Clay: In passing, one of the men in the gang is called “Clay.” This could be a reference to “John Clay,” the villain of the story “The Red-Headed League.” Holmes himself called John Clay “the fourth smartest man in London,” and many pastiches consider Clay part of Moriarty’s network. So while this is very likely an explicit canon nod, it’s also a pastiche nod.
Episode 213: All In The Family
Mafia: Believe it or not, the Mafia does make an appearance in the original canon. Sort of. The story “The Red Circle” references a few Italian organizations of the time, and the Red Circle itself is a renaming of the Black Hand (confirmed by a copy of Doyle’s original manuscript, where “Black Hand” is crossed out and “Red Circle” written in its place). At the time, the “Black Hand” was (incorrectly) used to describe both the Mafia and the Camorra, another contemporary criminal organization based around Naples. So, a roundabout reference to the Mafia, but one nonetheless.