The house & shed where the Wiccan coven held their meetings is the same as the exterior scenes of Melinda & Jim's house on Ghost Wisperer.
"The Book of Shadows" was first created in the late 1940s. The text contains rituals and spells found in the Wicca religion.
Nathan Gamble previously appeared in a Season 8 episode as the character Kobe Farentino. The episode is titled "Who and What".
Cyanide inhibits the body from using oxygen. The most common type of exposure to cyanide is from smoking.
Runic symbols are pre-Roman European symbols and were used by Nazi Germany to idealize the Aryan heritage.