Trivia about Batman: The Killing Joke.
- Based on the graphic novel of the same name by Alan Moore and Brian Bolland.
- This is the first DC animated film and the first Batman film to be rated R by the MPAA.
- Reunites Mark Hamill, Kevin Conroy, and Tara Strong who voiced the Joker, Batman and Batgirl in Batman: The Animated Series. They last voiced their respective characters together in Batman Beyond: Return of the Joker.
- Original comic writer Alan Moore wished to not have a credit upon the films release, instead, wanting the credit to go to artist Brian Bolland as well as have any profits generated be given to Bolland as well.
- Justice League: The Flashpoint Paradox director Jay Olivia wrote a Batgirl-centered sequence specifically for this feature film.