• Actor Allusion:
    • One of the books Sherlock pulls in attempting to crack the book cipher is Charles Darwin's On The Origin of Species -- Cumberbatch played Joseph Hooker in the Darwin biopic Creation.
    • It may not be deliberate, but one of our first sights of Martin Freeman in the first episode is in a dressing gown and pyjamas. One would assume that he knows where his towel is. In the second episode, Sherlock and John are called to a meeting at Tower 42. (That's its real name, by the way - it has 42 stories, but one assumes the owners knew what they were doing when they renamed it from the NatWest Tower.)
    • Remember Sebastian Wilkes (Bertie Carvel) from "The Blind Banker"? According to him, he and Sherlock graduated from the same university. Watch Hawking and have your minds blown. He's not lying.
    • John also spends an early scene is the second season finale wearing a bathrobe with a towel slung over one shoulder.
    • In John's blog he explains that one of the reasons he didn't post in the time between the first and second seasons was because he was "visiting a mate in New Zealand."
    • During the "memory palace" scene in "The Hounds of Baskerville," one of the words displayed is Ingolstadt, a German city that features prominently in Frankenstein. Benedict Cumberbatch alternated the two lead roles in Danny Boyle's stage adaptation of the novel.
    • Also in Baskerville, Russell Tovey plays a character who is extremely preoccupied with a fearsome wolf-dog-beast-thing. Not that he'd have any experience with that.
  • Casting Gag:
    • Sherlock's parents are played by Benedict Cumberbatch's real parents.
    • Mary is played by Martin Freeman's real life partner. It makes their chemistry much more natural and believable.
  • Descended Creator: Mycroft is played by Mark Gatiss, who is the co-creator of the series and a writer.
  • Dueling Shows: With Elementary, its CBS cousin. Sherlock has a two-season head start, but Elementary's pushing out more episodes.
  • Dyeing for Your Art: Both Benedict Cumberbatch and Mark Gatiss dye their hair black for their roles as Sherlock and Mycroft. They're both naturally ginger.
    • In preparation for the first season, Cumberbatch lost some weight to reflect Sherlock's tendency to not eat while working. In the second season, he gained the weight back - after all, Sherlock now shares an apartment with a physician.
  • Fan Community Nickname:
  • Fan Nickname: "Mocklock" has been used in a few comment threads for those that believe that the ambassador's children were kidnapped by someone disguised as Sherlock Holmes, which caused the little girl to freak out when she saw the real Sherlock. Also used to refer to the theory that the dead Sherlock at the end of the episode was a body double, possibly the same body that kidnapped the children.
    • Since the two producers work so closely together on this, their names have slowly condensed from "Steven Moffat and Mark Gatiss" to "Moffat and Gatiss" to "Moffat-Gatiss" to finally colliding into "Mofftiss."
  • Hey, It's That Guy!:
  • Hey, It's That Voice!: Peter Davison as the planetarium announcer in "The Great Game".
  • Lying Creator: Oh yes. Par for the course for Steven Moffat.
  • Oh Crap, There Are Fanfics of Us: Inverted. Back in July 2011, it was made clear to the Sherlock fandom--especially to the fans on Tumblr--that some of, if not the entire, cast knew about the porn that was being made by said fans. (Needless to say, this caused a panic.)
  • What Could Have Been
    • Matt Smith auditioned to play John, but was turned down for being more of a Sherlock.
    • When comparing the characterization of Sherlock in the unaired pilot and the canon, Sherlock comes across as far more sympathetic in the pilot. Considering the actions Sherlock is capable and willing to do in the series, this could ironically enough be a way of making him less creepy.