The film is based on real events. The Case of the Talking Moongose or of the Dalby Spook really took place in the Isle of Man in the 1930. A local family, the Irvings, claimed to have a spirit in the form of a talking mongoose called Gef. The case attracted the attention of skeptics and psychics alike, but most contemporary critics agreed it was most likely a hoax.
Christopher Lloyd and Simon Pegg have both appeared in the Star Trek film series.