In the film's opening scene, Holmes is seen smoking opium. It is subsequently implied that this is a regular occurrence. This represents a contrast from the character of the Conan Doyle stories, in which his drugs of choice were morphine and cocaine. In the stories, Holmes only smokes opium once as part of a disguise.
When he views the first dead body, Holmes quotes Lord Byron: "Oh! snatched away in beauty's bloom, / On thee shall press no ponderous tomb."
The bearded ambassador at the ball describes Holmes as the second-best criminologist in Europe, second only to the great Bertillon. He is referring to Alphonse Bertillon, the French police officer credited with the invention of the science of finger-printing and the standardization of mugshots in the nineteenth century.
Daniel Webb played Lestrade in Hound Of The Baskervilles but was not available to play the role again
Ian Hart previously played Dr. John Watson in Sherlock Holmes - Der Hund von Baskerville (2002). He also played Sir Arthur Conan Doyle in Wenn Träume fliegen lernen (2004).