Plot hole: Nick has spent two seasons with the supernatural ability to see perfectly well in the dark. But here, exploring the haunted house alone, he suddenly needs a big neon-blue-beamed flashlight to see where he's going.

Plot hole: The handyman tells the police that he has turned on the power to restore lights in the house. Why, then, is everyone still crawling through the place with flashlights?

Factual error: In the flashback to Nick's wedding night, his medieval tunic/shirt has 20th Century white plastic 4-hole buttons sewn to the cuffs.

Factual error: The costumes in the flashback to Nick's wedding are a mishmash of the mismatched, coming from several different eras, including a full metal suit of armor that's at least 2 centuries ahead of the flashback's period setting in the 1200s.

Plot hole: Nick mysteriously forgets that he can fly in this episode. With the ghosts of his past victims in hot pursuit, he trips and tumbles all the way down a full flight of stairs. Any other time, he'd simply have flown away.