10. The Bouncy Ball
Here's one for you to try at home: if you place a bouncy ball under your armpit, it stops the pulse in your wrist. Sherlock knew all too well about pulses being tells; it's how he worked out the code on Irene Adler's phone after all. And if you don't have a bouncy ball, just try a clenched fist. It doesn't work quite as well, but that's okay, it's not like you're
actually faking your death to avoid the assassination of Mrs Hudson. It just so happens that Sherlock was bouncing a ball in the lab. A coincidence? Possibly. What if the bouncy ball isn't even mentioned? It might not have to be. There are so many details, and this is one of the more straightforward ones; we could just assume that whether Gatiss explains it or not, the bouncy ball was used. The
real question, is how it stayed under his arm with his limbs flapping around.