Continuity mistake: While playing the piano in Justin Guthrie's apartment, he is bare handed. In the next scene when he gets up to point at the blood, he is wearing gloves. (00:24:12 - 00:24:42)
Other mistake: When Sherlock and Watson look at the coffee order from the trial it has the names of the 4 jury members who robbed the vault. Not the original men that did the robbery.
Chosen answer: M broke into the brownstone and left a note. Holmes deduced he was staying at a high-class hotel from the soap scent on the note, and gave a picture from a hidden camera to his "irregulars" on the street to stake out hotels. One of them saw him, so Holmes followed him to his next intended victim and knocked him unconscious with a baton.
Sierra1 ★