Visible crew/equipment: When Harry and Amos analyse the bathroom, the edge of the set wall is visible on the right side of the screen.
Revealing mistake: When Jessica visits the basement, there's plenty of light everywhere. She then turns off the light, but there's still plenty of light. However, when Adam Frobisher shows up half a second later, the whole place is now in darkness to allow for all the mystery and the intrigue.
Plot hole: When Beverly is killed the killer shuts off the main power switch which would have turned all the lights off in the house, not just those in the bathroom. (01:31:00)
Answer: It was never revealed what caused Frank's death.
raywest ★