Fanon: It's become common for people to think of Mal as non-binary and Jackrum as a trans man. It's helped by the way Mal is written uncomfortable with identifying strictly within male and female gender roles, to which Polly states "you're you."
Genius Bonus: In-universe, a few characters get Polly's references to the folk song "Sweet Polly Oliver" when creating her male alter-ego (although those that do are already smart enough to have figured her out anyway).
Anyone familiar with the quotation which the title refers to will probably figure out that all the recruits are women fairly early on.
Les Yay: Aside from Tonker with Lofty, Wazzer and Maladicta get very close with Polly.
Stealth Pun: A very well hidden Stealth Pun that might be accidental. A mystery voice giving Polly some advice and a pair of socks says: "You don't bulge where you shouldn't bulge, but you don't bulge where you should bulge. People notice whats missing more than they notice what's there. Just one pair mind you. Don't get ambitious." Some tropers might notice words that are missing, like "Don't get cocky".