A scene shows Oliver and Felicity watching a news broadcast with a woman protesting against the use of the "Partical Accelerator", the machine that caused the accident which turns Barry Allen into The Flash.
The title of the episode is an incomplete quote from " The Godfather Part II". The complete quote is, "My father taught me many things here - he taught me in this room. He taught me - keep your friends close but your enemies closer." This has often been attributed to Sun Tzu and sometimes to Niccolò Machiavelli or Francesco Petrarca, but there are no published sources yet found which predate its use by Mario Puzo and Francis Ford Coppola In their screenplay.
Michael Germant (Bartender) will go on to appear in another 'Arrovwverse' TV show but as another, unrelated character. He appears in an episode of 'Legends of Tomorrow' as a German Sailor.