Trivia: At approximately 29 minutes in, Ernie Hudson says "Who ya gonna call?" He is one of the original Ghostbusters from the 1984 film and this was the popular tag line in that movie.
Crisis on Infinite Earths: Part Two - S1-E9
Trivia: The version of Batman played by famous Bat-voice Kevin Conroy is a darker version of that from the graphic novel The Dark Knight Returns. The line "the world only makes sense when you force it to" is a version of a line from that comic (also used in Batman V Superman), also "Clark always said yes to anything with a badge or a flag." There are also elements from Batman Beyond, which first aired in 1999 (hence Earth-99), in which Conroy voiced an older Bruce Wayne mentoring a new Batman. The whole scene is full of nods to other versions - describing Kryptonite as "a little souvenir from the old hometown" is a Lex Luthor line from the original Superman movie, and him describing Superman as "strange visitor from another planet, with powers and abilities far beyond those of mortal men" comes from Superman serials from the 40s and 50s.