Having recently re-watched most of the series with friends (in a highly successful bid to introduce them to it), I began to notice some cultural references on the part of the writers:
1) ‘A Scandal in Belgravia’ bears a strange resemblance to the Martin Amis novel Yellow Dog, and is highly likely a tip of the hat. Both share the following features:
-a Royal scandal involving footage of a sexual nature
-the scandalous material is used as leverage for protection
-a subplot involving a plane crash
-a woman in the sex industry tries to seduce a man with hidden motivations, ultimately in vain
2) Steven Moffat and Mark Gatiss and Stephen Thompson are probably Smiths fans. In The Reichenbach Fall:
-Kitty Riley: ‘You’re going to need someone on your side.’
-Sherlock and Watson run in front of a double decker bus (‘There Is A Light That Never Goes Out’)
3) ‘A Study in Pink’ was *possibly* inspired by the X-Files episode ‘Tithonus’.
-In both episodes, a serial killer is suspected to be behind a string of strange deaths, but none of the investigators can exactly explain how a murderer theoretically could have done it.
-The suspected murderer takes the lead investigator (Scully in the X-Files) for a car ride to explain how he did it.
-The investigator almost dies as a result in the end, only to be saved by a colleague.
4) The end of season 3 is likely a (fucking awesome) reference to the Max Headroom broadcast signal intrusion. Doubling the goodness and bringing the intertextuality full circle, one of the broadcasts made by the still-to-be-found intruder 30 years on was during Doctor Who, a show that was also later revived by Moffat and Gatiss, the creators of Sherlock.