The synopsis for the mini episode reads: "A series of seemingly unconnected crimes stretching from Tibet to India to Germany. Sherlock Holmes has been gone for two years. But someone isn't quite convinced that he's dead..." This refers to Philip Anderson, a recurring character in the series. He tried to convince Greg Lestrade, another detective, by telling him about certain events that took place in Tibet, India, Germany, and other locations. However, Lestrade was convinced that Sherlock was dead, and tells Anderson he should stop investigating. Lestrade went to visit John, who has moved out of Baker Street since Sherlock's death. He gave John some of Sherlock's old items, including a video message from John's birthday. In the message Sherlock states that he will see John very soon and tells him to have a good birthday without him as he is 'busy'.
In the "Trepoff murder" case, a jury is shown deliberating on the defendant's guilt in a Hamburg court. In fact, as the German judicial system is (and has been for two millennia) based on Roman law, not Anglo-Saxon law, there is no jury system in Germany. Criminal trials are decided by a court consisting of professional judges and additional lay judges.