Plot hole: It's stated multiple times that the Semper Apex server room is protected from wireless signals, but Sofia's team sneaks in and plants a "ghost jack" with a wireless transmitter on it, which they say is slaved to an IP address. Except that wouldn't work in the server room. There'd be no way to get a signal to or from it.
Character mistake: The American Flag is hung improperly on the wall. The Flag's union (stars) should be at the top, to the observer's left, but it's to the observer's right. (00:06:38)
Continuity mistake: At end of the episode, when Sherlock leaves Detective Bell outside the 11th Precinct, Bell had a book and an envelope of which Bell puts the envelope in his pocket leaving the book, the next shot shows Bell turn and throw the envelope in the trash and the book disappears. (00:39:15)
Character mistake: Sherlock and Joan are looking at video footage of a restaurant called "La Porte Blanc", which is incorrect French. The right way is "La Porte Blanche."
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 ★