While re-watching Scandal in Belgravia (episode 1 season 2 of Sherlock) I found this little shot. I like the coffee cup with the spirals reminicent of question marks so that it could almost be a Doctor Who reference. I also am not surprised that Sherlock leaves the milk out on the shelf next to the picture frame full of beetles. The thing that has me smiling though, is the Cleudo game stuck in the wall with a knife!
In episode 2 season 2 the Hound of the Baskervilles, Sherlock suggests that they play Cleudo ( In the US we call the game Clue). John says that they are never playing the game again because it is not possible for the murderer to kill himself.
This is triply funny when you realize that the plot of the story of the Aluminium crutch that everyone keeps mentioning is the victim set up his own death.
Other hidden Items include the IOU in the background of the Reichenbach fall. It’s hard to even call them hidden because they are in plain sight, but still it is hard to notice them. Ever we see but do not observe.