The mythology and folklore books that Dr. Jon Holland consults include "D'Aulaires' Trolls" (1972) by Ingri and Edgar Parin d'Aulaire, "The Magic Tree: A Tale of the Congo" (1973) by Gerald McDermott, "Leprechauns, Legends and Irish Tales" (1988) by Hugh McGowan, "Sir Gawain and the Green Knight" (1994) by David and Mark Shannon, "Baba Yaga and Valisia the Brave" (1994) by Marianna Mayer and "Folklore" by Mark Francis.
The title is based upon the childhood fear of "monsters under the bed" and that appears to be true in this show.
The search helicopter briefly seen is an MD Helicopters model MD530F.