Though this story is listed late in the first season, it takes place before several of the others. In addition to the obvious second appearance of the Injustice Gang in "Fury", Luthor wears his new battle armor in "Legends", and Flash makes reference to Solomon Grundy in "The Brave and the Bold".
In the comics, Ultra-Humanite was Superman's nemesis until Lex was introduced.
Luthor's group pays tribute to the Injustice Gang from the incredibly popular JLA comic (Revamped by Grant Morrison) and the Legion of Doom from the Super Friends (1973) cartoon. Lex Luthor forms the Injustice Gang, as he did in the JLA comics, and wears a costume almost similar to that which the Luthor character wore in various SuperFriends episodes. Lex Luthor, Solomon Grundy, and Cheetah (albeit the modern day version) are the only characters from the Legion of Doom. Lex Luthor and The Joker are the only two characters who were in the Injustice Gang in the comics.
Included as a bonus cartoon from the DC Comics Vault on the blu-ray release of Injustice (2021).