Sherlock Holmes: If you eliminate the impossible, whatever remains, however improbable, is the truth.
Sherlock and Watson are riding in a limousine. They are seated on the back-facing seats of the limo. Thee are 2 passengers seating on the back seats. The street background visible through the back and side windows shows traffic and the limo moving forward. Some shots of Sherlock show the background traffic moving in the right direction (backwards) and one shot shows traffic moving in the opposite direction, as if Sherlock was seating on the back seat or the limo was moving In reverse.
Sherlock's brother Mycroft has an international franchise of restaurants called Diogenes. This is a reference to the Diogenes Club, the gentleman's club Mycroft co-founded in the Holmes short stories.