Edwin Payne and Charles Rowland, a.k.a. The Dead Boy Detectives, are characters from DC's Vertigo imprint of comic books. They debuted in Neil Gaiman's Sandman series (issue 25) in 1991.
Charles' glowing blue baseball bat is a homage to Matt Wagner, co-creator of the Dead Boy Detectives. Wagner also created Kevin Matchstick, who wields a magical blue baseball bat in the Mage series.
Ruth Connell (Night Nurse) starred as Rowena in Supernatural, the mother of Crowley, played by Mark Shepherd (Willoughby Kipling).
Michelle Gomez (Madame Rouge) played Missy during the reign of the 12th Doctor in Doctor Who. Ty Tennant (Edwin) is the adopted son of David Tennant who played the 10th Doctor and the grandson of Peter Davison who played the 5th Doctor.
Madam Rouge's tunneling time machine is made to resemble the Venusian creature from the 1956 movie "It Conquered the World".