Ends with a dedication card reading "In memory of our friend Eric Justen." Justen was the show's re-recording mixer since its pilot episode. Justen passed away from a heart attack on August 11, 2016, two weeks shy of his 44th birthday.
Sherlock says, "trust your instincts though they render no reason". This is a paraphrased quote from Ralph Waldo Emerson. The original is, "Trust your instinct to the end, though you can render no reason."
The antagonist in this episode is often referred to as "The Bensonhurst Bomber". Anyone who's a fan of The Honeymooners knows that Ralph Kramden was dubbed The Bensonhurst Bomber in one of the most popular episodes of that beloved series. It seems only fitting that someone on Elementary should have acknowledged that well-known reference, yet it wasn't done.