Set to be the final movie in the DCAMU (DC Animated Movie Universe).
Hynden Walch, who usually voices the character 'Starfire' in Teen Titans, voices Harley Quinn in this movie.
The Mobius Chair that Batman sits on in the film has god-level intelligence from its inception from another New God. In the comics, Batman only asks it two questions: who killed his parents (it answered Joe Chill) and who is the Joker (the Chair replied without a name but saying there's actually 3 Jokers).
Rebecca Romijn (Lois Lane) and Jerry O'Connell (Superman/Clark Kent) are a married couple in real life since 2007.
Batman's suit is reminiscent of the 'Hellbat' suit from the comics where it was forged in the Sun and built with features by each member of the Justice League to allow Batman to fight god-level threats as Superman does. It is also similar to Terry McGinnis' (New Batman) revamped incarnation of the Batsuit too.