The second series concluded with "The Reichenbach Fall". Steve Thompson wrote the episode, which was directed by Toby Haynes, who had previously directed many of Moffat's Doctor Who episodes. First broadcast on 15 January 2012, the episode follows Moriarty's plot to discredit and kill Sherlock Holmes, concluding with Holmes faking his suicide as Watson looked on. It was based upon Conan Doyle's story "The Final Problem", in which Sherlock and Moriarty are presumed to have fallen to their deaths from the Reichenbach Falls in Switzerland. Moffat felt that he and co-creator Gatiss had outdone Conan Doyle in their version of Holmes' fall and Moffat added that, in that much-discussed sequence, there was still "a clue everybody's missed"The Wikipedia article lead me to this quote from Moffat: "It's not a cheat. We've worked it out. It all makes sense."
I decided to go back and check out the rooftop sequence. I'm pretty sure I spotted the clue he was talking about (hint: it occurs very early in the scene) and I believe I've got the rest of the clues as well. I'm putting them after the break. If you feel like playing along, scroll down but be warned, it's all spoilers and nerdiness from there on.
I always feel a bit guilty, or at least apologetic, about this kind of post. God knows I've made fun of plenty of fanboys in my time. I will, however, offer a couple of defenses for this one case: first, Moffat really is inviting us to go for it; and second, one of the most appealing traits of this generation of British TV writers is the care they take not to abuse our suspension of disbelief. Once we've accepted the premise, they will make sure that everything that follows, no matter how surprising, will be believable in terms of plot and consistent in terms of character.
The first time I watch a Moffat and friends show, I simply go along with the effective drama and comedy. Later, I'll peek behind the curtain and look at the machinery, but when the story's good enough, that just adds to the fun
I'm sure I missed something (and that other viewers have already noted all of these points) but here's my take:
Before jumping, Holmes talks about magic tricks. He seems to be talking about his feats of deduction but it also describes the fake suicide, which includes confederates, misdirection and limiting the perspective of those being fooled
Though not in the scene I reviewed, I remember Holmes asking an important favor of pathologist Molly Hooper. The rest of the clues slipped by me on first viewing -- I was too caught up in the story -- but they were fairly plain when went back over the scene.
The first shot on the roof appears to be taken from a robot cam (I'm pretty sure that was the clue Moffat referred to). Someone was remotely viewing what was happening on the roof of the hospital (that's also significant) thus allowing the people on the ground to coordinate their actions with what's going on above.
Shortly after Holmes arrives, Moriarty observes that a crowd is starting to form. A flatbed truck with an oddly nondescript cargo also pulls up. Because of the small building in front of the hospital only those people will actually see Holmes hit the ground. Before starting to jump the first time, he asks Moriarty for "privacy," to step back so that he won't actually see the fall.
When Watson arrives, Holmes insists that he should go back to his original position where the small building blocks his view.
Immediately after the fall, Watson is hit by a cyclist, both delaying and disorienting him. By the time he gets to Holmes, a ring of people have already formed around Holmes, including some remarkably fast first responders (even for a suicide that happens in front of a hospital). The truck, which I assume carried a high fall airbag, pulls away unnoticed.
If anyone has an alternate theory, the comment section for this post is obviously spoiler-friendly.