The document discusses several key motifs in the film "The Dark Knight".
1) The use of dogs represents how society breaks down into a "dog-eat-dog world" when order is disrupted, as the Joker uses attack dogs to turn people against Batman.
2) The Joker's theme music underscores his sinister intentions, with a more dramatic tone when he plans to cause trouble.
3) The Joker's card serves as both a warning and a "stamp" claiming responsibility - it signals the audience when the Joker is involved in events.