Revealing mistake: Before John Watson closes the laptop, the screen displays a phone tracking website in the Chrome web browser, supposedly at Mephone.org.uk. In the URL address bar, however, "file:///C/http/mephone.org/mephone.html" is visible which is a standalone HTML file on the computer's hard drive. (01:08:35)
Revealing mistake: In the bank where Sherlock is trying to get a view of the painting with the Chinese numbers, he backs into a pillar, which wobbles. (00:11:25)
Revealing mistake: While Watson and Sherlock talk about the deceased banker and the crime scene photographer takes pictures of the dead body you can see the "corpse" breathing, as the buttons on his waistcoat are moving. (00:14:50)
Revealing mistake: When you see Sherlock and Watson in the museum, Sherlock leaves and nearly gets shot. You see him dive behind the large statue, which moves. That's unusual for a large statue, but looking closer, you can see there are wheels attached to the base. (00:49:35)
Revealing mistake: When they are watching for vases, the auction website has no proper domain. It is loaded locally from the C:\ drive. (00:55:00)
Revealing mistake: The banker shoots himself with a Sig 226R. When you see it lying on the bed it has a screw missing from the grip. In the first episode, Watson has a gun in his desk drawer. It is a Sig 226R also with a screw missing from the grip. Obviously they only have one prop gun.
Chosen answer: That line of dialogue has never actually been spoken in any of the Sherlock episodes, during seasons 1-4. However, that line is written in someone's fan-fiction story online, where it's said by Sherlock and directed at Anderson.
Super Grover ★