Sherlock: 20 Easter Eggs, In-Jokes And References
17. Many Happy Returns
Before series three began, the BBC released a seven minute online prequel to the series which saw Anderson share his evidence for Sherlocks survival with Lestrade. As such, this basically resulted in it being one long string of references to the Canon.
Two of the most notable include a yellow face mask hidden in a box of Sherlocks things. This refers to the short story The Yellow Face (although it doesnt actually feature such a mask). The other is a nod to a case mentioned in The Six Napoleons. Here, an Indian detective tells how he (really Sherlock) deduced the killers whereabouts due to how far a chocolate flake had sunk into the victims ice cream cone. This is a modernising of how Holmes deduced a crime by the depth to which the parsley had sunk into the butter upon a hot day.