Final credited appearance of Phil Morris as recurring character John Jones/Martian Manhunter. He would appear uncredited in the character's final appearance of the series in Salvation (2010).
In the comics, Checkmate is a covert operations group within the DC Comics universe, divided in White (Information) and Black (Black Ops), with the royals (King and Queen) of both colors as the supreme leaders, Bishops as tacticians, Knights as higher-level operatives, Rooks as Internal Affairs officers and Pawns as low-key operatives and helpers to the overall Checkmate cause. Amanda Waller leads Checkmate White as the White Queen.
When Amanda tells John Jones that he has phobia to fire, it's alluding to the fear of Martian Manhunter to fire because his planet was destroyed by fire.
Oliver's Arrows in this episode: Mini Dart, Taser.
A WWII propaganda poster is seen in the background. In the scene when Clark leaves Chloe behind to ask John Jones about his involvement with a man's death, the poster "Loose Lips Sink Ships" is seen in the background. It may be a nod to government conspiracies and patriotic propaganda, a common theme in Checkmate's words. Chloe uses these exact words in "Arrival" "Loose lips sink ships and God knows I've sunk my share of flotillas", when she confirms her understanding on why Clark never told her his secret before.