How Shelock did it? Moffat, the co-creater of the Sherlock said that there is,", "and there’s one clue that everyone’s missed. It’s something that Sherlock did that was very out of character, but which nobody has picked up on."
--I don't know what this means, as detailed below and elsewhere, there are many out of character things sherlock does. Others have mentioned that the nervous twitch with the ball is strange or that the different views and vantage points of Saint Bart's don't line up. While I can understand that the ball may be Sherlock trying to figure out the vector that he can fall at, I don't see where to got from there. I certainly don't know anything about London.I also hope the answer is not something stupid like he switched places with Molly and she died or he jumped on her and then switched. One thing that occurs to me is that it is obvious is that Sherlock realized that the key code etc is fake as 1) he knows music and 2) why did he ask Moriarty to come to the roof (!) of all places unless he had it all worked out beforehand to stage his death and was trapping Moriarty. He clearly wants the roof. Either way, excluding all the deus ex machina suggestions (and the idea of using a hologram), I have been wondering about all the water on the ground and if he did not somehow use a silver iodide generator (used for cloud seeding) to cushion his fall. Either he had it under his coat or Molly sprayed it out before. That would account for all the water and the short bit of rain afterwards. I believe silver iodide in nature becomes a softish substance, that could cushion his fall. Of course another posiblity would be using either a hologram or "more simpler" (in a macgyver sort of way) would be what is called a percived hologram, like they have in haunted houses. More on both can be found at avconcepts.com. This may also call for moisture and maybe that is what there is water etc. Now if what fell is only a projection what was out of character? Dropping the phone ( a necessary if switching from real to fake) ? There is moment when he jumps that it seems that he could have a guy wire attached to the antenna behind him. 



http://www.radiotimes.com/news/2012-01-19/sherlock-what-is-steven-moffats-missing-clue