During a conversation around the 35-minute mark, a sign can be clearly seen in the background for the "Bam² Muay Thai Training Center." This episode was directed by supervising stunt coordinator James "Bam-Bam" Bamford.
The trivia items below may give away important plot points.
The character of Prometheus is normally portrayed as a villain of Batman, his exact criminal replica with a similar origin story, only reversed. He has also faced the entire Justice League at the same time and beaten them all.
Prometheus seems to be the baddie this season. In DC comics Prometheus is the villain that kills Roy Harper's daughter, Lian, and whom Green Arrow kills because of it. Green Arrow is arrested and jailed, gets thrown out of the Justice League and Black Canary divorces him.