First "DC Universe" animated film to feature the character of Swamp Thing.
"Justice League: Dark" is the second animated DC animated film with an R rating, though the content is closer to PG-13. It still didn't get an MA15+ rating in Australia like "Batman: The Killing Joke" did which in America was the first R rated DC animated film.
The "Demons Three" who appear at the beginning of the movie are the sons of Trigon and half brothers to Raven in the DC comics universe.
The animated film will be part of the DC Animated Movie Universe established by Justice League: War (2014).