Action Girl: Batwoman, of course, but Sonia is an accomplished police detective before the film even starts. The Penguin's Bodyguard Babes count as well.
Actor Allusion - Like her voice actress Elisa Gabriellia, Sonia has a beauty spot on her left cheek.
Art Shift - This film was made after the "revamp," which was an artistic redesign between the original animated series and The New Batman Adventures, and was drawn in the style of the latter. Rupert Thorne had never appeared after the original revamp, so a new design had to be created to match his character with the art-style of the rest of the film. Though more "streamlined," it is nigh-identical to his previous design.
Batwoman - A re-imagining of the character, originally created in 1956. Her original identity is alluded to with Kathy Duquesne, whose name is phonetically similar to the original Kathy Kane.
Bittersweet Ending: Predominantly more sweet than bitter, but it is not without its sadness. Rocky gets her fiance out of jail and Kathy gets her family out of the mob business, but Sonia is forced off the police force.
The Chanteuse: The unnamed singer who performs "Betcha Neva" in the Iceberg Lounge.
Collective Identity - Batwoman is all three of the suspected women, working together to pose as a single multi-skilled crime-fighter.
Dating Catwoman - Bruce goes out with Kathy, daughter of notorious crime boss Carlton Duquesne, a few times. Given that he is the Trope Namer, this is not surprising.
Deadpan Snarker - Alfred, as per usual, and Tim Drake gets in a few good ones as well.
Roxanne: Yeah. Fortunately my boyfriend is very understanding. What about yours? *pause* Girlfriend, I mean! Of course, girlfriend! I mean, considering your reputation and- NOT that it's bad or anything or even any of my business, because it's not, I was just curious! *stops suddenly* How red is my face?
Let's You and Him Fight - Played with. Batman is out to stop the reckless Batwoman, but in their first face-to-face encounter he comes to her aid when she is surrounded by Mooks. They later have a scuffle, but there is no real misunderstanding at work - she just does not want Batman to stop her.
Lighter and Softer - As compared to other Batman animated films. In the clearest departure from its roots, more scenes take place in the daytime.
Omnidisciplinary Scientist: Batwoman is a brilliant martial artist who also invented miraculous gadgets and is a skilled and experienced computer hacker. It turns out it is three different women using one costume who each bring their own skills to the table.
The Other Darrin: David Ogden Stiers replaced Paul Williams as the Penguin and Hector Elizondo replaced Henry Silva as Bane.
Barbara: But... spring break will be coming up soon and I'll be back in Gotham for two whole weeks. (*suggestively*) Won't that be nice. Bruce: ... Yes. We'll all be happy to see you. Tim: Don't drag me into this.
Shout Out - The original Batwoman, Kathy Kane, is referenced by the identity of one of the women potentially behind the mask: Kathy Duquesne.
You All Share My Story - Rocky, Sonia, and Kathy all have a beef either with a Bat-villain, or Carlton Duquesne. More indirectly, each shares a trait with Batman: Rocky his intelligence, Kathy his wealth, and Sonia his determination.