Trivia: The Christmas ball scene is symbolic: since it is a masquerade party all the guests are in disguise. The only guests who aren't wearing masks are Bruce Wayne and Selina Kyle. This implies that their real personalities are Batman and Catwoman respectively, and that their public persona is the real disguise.
Trivia: Michelle Pfeiffer actually became quite skilled with her bullwhip behind the scenes. In fact, the scene where she whips the heads off the mannequins one after another was 100% real, and accomplished in only one take with multiple cameras set up. As soon as "cut" was called, the entire crew burst into applause, shocked by how precisely and perfectly she nailed the scene.
Trivia: The film initially had a rather lucrative McDonald's Happy Meal tie-in which included "Batman Returns" toys with every meal. After the film was released, parents complained about its dark imagery and cynical themes, and McDonald's began to re-market the toys as simply general "Batman" toys as opposed to "Batman Returns" toys. The toys themselves were considered something of a rarity for some time, as a rumor was started that McDonald's pulled the toys from market.
Trivia: Dustin Hoffman was the first choice to play The Penguin.
Answer: The film keeps it ambiguous. There are two ways to look at it. Scenario A- She literally died and is brought back to life by the alley-cats somehow, adapting some of their traits. Or... Scenario B- The trauma of falling and sustaining a head-injury, along with her paranoia after Schreck tried to kill her, has driven her mad, and she uses her connection with cats to build a new persona. (Which is supported by the fact that all the things she claims "kills" her with each of her "nine lives" wouldn't actually have killed her. Ex. Her one fall is broken by the kitty-litter truck. Max doesn't hit her in any vital organs when he shoots her. Etc.) Her destroying her apartment is her lashing out at all the things she used to hold dear- her vision of a normal life, etc. It's symbolic of her purging the past and embracing the future. (Plus, oftentimes when people throw fits, they'll smash stuff up).