Lena recognizes Parthas, Nia's hometown, as a word of Irish origin, "paradise." Katie McGrath is herself Irish, and her native accent has briefly slipped out in several previous episodes.
In the comics, the Dream Power is not exclusive to either gender.
At the beginning of the episode, Kara, Alex, Lena, James, Nia and Brainy are seen playing Exploding Kittens, a popular card game published by The Oatmeal.
Brainy identifies the source of radiation in the frat boys' drugs as gamma rays, which, in Marvel comics, is the same source that turned Bruce Banner into the Incredible Hulk.
The scene with purple energy arcing across the globe shows that Earth-38 has a major difference from this one: a sea running the length of California, such that the state forms one vast northward-jutting peninsula.