There are a total of twenty-five credited cast members in this episode. There are a total of twenty-six characters featured in this episode (not counting background extras). David Harewood plays both Hank Henshaw and J'onn J'onzz.
This episode foreshadows the notion that Jeremiah Danvers may in fact still be alive.
The character of Colonel James Harper is based on the DC Comics character, Jim Harper, who was a costumed adventurer who called himself Guardian. He was created by writer Joe Simon and artist Jack Kirby and first appeared in the first story in Star-Spangled Comics #7 in April, 1942.
The character of Rick Malverne is based on the DC Comics character, Dick Malverne, who grew up in the same orphanage as Linda Lee Danvers, aka Supergirl, and later became her love interest. The character first appeared in Action Comics #256 and was created by writer Otto Binder. He was originally named Dick Wilson in this inaugural appearance.