Visible crew/equipment: When Sherlock and John get into the taxi in Baker Street (leaving to go to the scene of their first case) you can see a filming crane reflected in the back of the taxi.
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)
Continuity mistake: When Sherlock steps out of the taxi on Baker Street three extras walk by. First, it's a lady with her back to the camera, wearing a dark jacket, purse, boots and a dark curly hair. Next, the two women walking towards the camera. Notice the blonde one on the left with the pony tails, dark jacket with the multi colored cloth at the bottom, and grey pants. Fast forward to when the taxi pulls up to take Sherlock and Watson to the the crime scene. As Sherlock opens the taxi door, the same first lady with the curly hair and the blonde with the ponytail are now walking together in the same direction the blonde was walking when Sherlock arrived. (00:12:58 - 00:17:51)
Continuity mistake: Early in the episode Sherlock and Dr. Watson enter a cab in daylight for a ride to the crime scene in Brixton, which is a part of greater London. It is night when they arrive.
Other mistake: Watson never orders, but somehow while in Angelo's, he has a full plate of pasta.
Continuity mistake: As Sherlock and Watson come out of their apartment to hail a taxi to be taken to Brixton and the scene of a murder, two extras can be seen in the shot - one crossing the road and one walking up the far side of the street. At the top of the street there are two white colored cars, but they suddenly disappear, to be replaced by a dark colored car. Also the light of the building across the road is suddenly turned on.
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 ★