Luke Fox mentions a breakout at Arkham Asylum, a reference to the Elseworlds crossover event from 2018.
When Beth sees a news report of the search for her, it's mentioned that the search has expanded to Blüdhaven, which, in the comics, was the city Dick Grayson protected as Nightwing.
Johnny is the first case of gender-bending in Batwoman since he's based off of Jane Cartwright aka Jane Doe, a serial killer with a hideously disfigured face who wears a face mask to become someone else and is able to mimic any voice she heard. Interestingly enough, in the Gotham (2014) episode "Nothing's Shocking", a variation of Jane Doe named Jane Cartwright is the main villain. Johnny is also the second case of gender-bending in the Arrowverse where a female character was changed into a man. The first is Lucius Coolidge from the Season 3 episode of The Flash (2014), "Cause and Effect" (2017). **A white mask can be seen at the Cartwright house, which is a reference to Jane Cartwright (whom Jonathan Cartwright is based on). Jane's mask, in turn, was based on Calendar Girl's mask
"The Mouse's Tale" is a shaped poem by Lewis Carroll which appears in his novel 'Alice's Adventures in Wonderland'. Though no formal title for the poem is given in the text, the chapter title refers to "A Long Tale" and the Mouse introduces it by saying, "Mine is a long and sad tale!"
Kate has white eyes on her cowl when she uses its night vision function, making her look similar to her animated counterpart from Batman: Bad Blood (2016) (and most animated depictions of the Batfamily in general).