Reina Del Agua translates from Spanish to English as The Queen of Water
Ray McKinnon (John Proctor) appeared in Deadwood which starred Kim Dickens (Madison Clark) and Dayton Callie (Jeremiah Otto). All three actors appear in this episode.
The scenes of Madison floating in the aftermath of the dam collapse were shot in a giant water tank.
This is composer Paul Haslinger's final episode for the show. He was replaced in Season 4 by Danny Bensi and Saunder Jurriaans.
Oddly, for a show about zombies, there aren't any in this episode.