Lex Luther refers to Area 52 as "the New 52." This is a reference to the rebrand of DC Comics that launched on September 2011.
This film features four previous voice actors for the Joker. Troy Baker voiced the Joker in Batman: Assault on Arkham, John DiMaggio in Batman: Under the Red Hood, Kevin Michael Richardson in The Batman, and Mark Hamill in Batman the Animated Series.
Mark Hamill reprises his role as the Trickster.