Morrow has a collection of clippings referencing various disappearances of mad scientists, including: Doctor Sivana (from last issue); IQ (Hawkman adversary); Doctor Death (Batman adversary); Jeremiah Clugg (Blue Beetle adversary); Doctor Tyme (Doom Patrol adversary); and Doctor Cyclops (nod to the Simpsons character).
Credits include "Special thanks to Joe Prado."