Revealing mistake: Just before Walter throws Lisa through the window, you can tell that Lisa is a stuntman wearing a wig.
Prince of Darkness (1987)
1 revealing mistake
Directed by: John Carpenter
Starring: Donald Pleasence, Victor Wong, Jameson Parker, Lisa Blount
Continuity mistake: Susan and Lisa are standing perfectly still for a long time awaiting the transformation of the possessed girl, yet Lisa's hair goes from being behind her back to over her front then back again when the possessed girl "wakes" up.
Father Loomis: Why weren't we told the truth?
Professor Edward Birack: Without the technology to confirm? It would have been another legend.
Father Loomis: But he was OUR prisoner, not yours.