Michael Biehn accepted his role the day after his father died. He wanted to keep his mind off his father's death.
A delivery truck parked in an alley where Rossi and Detective Fullwood are talking has a sign on its side that says "Bernero Linen Supply." Edward Allen Bernero is an executive producer of the series.
Ed Gein was never charged for most of his crimes. After his arrest for a murder where he quite literally left his signature (on a receipt) at the abduction site, Gein admitted to one other murder and robbing 10 graves. Parts of these bodies were found in use in his house, but he was only prosecuted for the second murder.
Gein's life was so tragic and shocking it inspired several characters in film and literature.
The female skin bodysuit inspired Buffalo Bill from The Silence of the Lambs, human face masks inspired Leatherface from The Texas Chain Saw Massacre (1974), and the abuse he suffered as a child and the resulting obsessive, Oedipal love for his mother, even after her death, inspired Norman Bates from Psycho.
Ed Gein was found guilty of murder, but declared insane and committed to an asylum. Following his death from cancer Gein was buried next to his mother, in the very cemetery he had desecrated during his life.
When Prentiss talks to the Unsubs father about their Au Pair, Abigail Hansen, he says she was from Denmark, to which his wife corrects him by saying she was from the Netherlands. However, Hansen is a Scandinavian last name and the third most popular last name in Denmark so it makes sense for the father to remember her as being from Denmark.
Randolph Mantooth, who plays the father of the unsub, Roderick, starred in Emergency! (1972) as a paramedic named John Roderick Gage.