The shot of the future news paper includes a headline about Wayne Tech and Queen Inc. merging. This refers to the companies founded by the respective families of Bruce Wayne (Batman) and Oliver Queen (Green Arrow).
William Tockman, aka Clock King, is a comic villain who made his debut in World's Finest Comics #111 (August 1960). His fixation with clock-related crimes began when doctors told him he only had a short time to live. He began robbing banks to set up a fund to take care of his disabled sister. He has run afoul of both Batman and the Green Arrow.
Farooq, aka Blackout, is a comic book character who made his debut in Flashpoint Vol.2 #1 (July 2011). In the alternative Flashpoint time line, Blackout is recruited by Cyborg to help stop Emperor Aquaman and Wonder Woman's war to conquer Europe.
Robert Knepper, who portrays William Tockman aka the Clock King, previously co-starred on Prison Break (2005) with Wentworth Miller and Dominic Purcell who portray Captain Cold and Heat Wave respectively on this show.