Having picked a bit more on this movie since I saw it, here are some thoughts on the feminist themes it picks up. Because as I read somewhere, this film is the girl's restroom in a nightclub, and it feels like an apt comparison. It shows a lot of the ways that girls or women both can tear each other down, and how they can build up and protect each other.
The plot opens with Harley reacting to malicious girl gossip, that she will only run back to Joker as soon as he beckons. In another scene, Black Canary chooses to stand back as Black Mask publically humiliates a woman and forces her to strip. We also have the scene where Renee Montoya's ex-girlfriend rats on her, despite wanting to help. We get to see the strategies that women use to adapt to and to survive in the patriarchy: in effect how patriarchy corrupts women as well.
Then we have a key scene where the movie's thesis on Black Mask explicitly becomes text, as Black Canary sings in Roman's nightclub. He is literally lost in the wilderness, lost in the bitterness, lost in the loneliness. But while the original song sings from the perspective of a man to another man, and takes a possessive slant, Jurnee Smollett-Bell's
performance of the song changes it to be about men who are
unable to see women.
But then the movie sets out to build models for female solidarity. Black Canary might want to keep her head down and most certainly not be a hero, but she's unwilling to let Harley Quinn be abducted, no matter what she thinks of her as a person. She might not be willing to inform on Roman, but she is willing to go against him in order to help Cass. Harley Quinn notices hair issues and lends a hairband. The characters consistently points out how great and awesome the other characters are. Perhaps most importantly, they are shown to trust each other.