Poison Ivy's carnivorous plant Frank is an homage to Audrey II the monster plant from Little Shop of Horrors (1986), and is named after that film's director Frank Oz.
After completing season 1 and easing deeply into the voice of Harley, Kaley Cuoco actually went and re-recorded the first episodes to have a more consistent voice.
The first Warner Bros. Animation series to be rated TV-MA.
Margot Robbie, who plays Harley Quinn in the DCEU, says she watches the show and is a fan.