There's strong, bloody animated violence throughout, some a bit more severe.

In a scene from Under the Red Hood, a character's mask malfunctions, and his head explodes offscreen onto the wall with blood

Definitely a lot more language than your typical animated "Batman" movie. It definitely deserves its R rating.

2-3 middle fingers, a few uses of "hell", plus 1-2 a-words

Dark, with some versions having key characters die in violent ways.