Plot hole: Miles explains the presence of the white bracelets that the Efficient Man slapped on their wrists as biorhythm monitors that act as keys for their room, each assigned to a chakra. Blanc's presence was not expected or announced, but not only Ethan Hawke had an unexplained spare bracelet, but he is also assigned a room, when there are 7 chakras and he brings the guest count to 8. It should also be noted that supposedly they are the "key" to each room, and yet Andi comes and goes from them as it pleases her (ironically the very sort of mistake that birthed the term "Fridge logic") and nobody wears them for the rest of the movie at all because the gag ran its course.
Plot hole: The spell Magicae Maxima works, but it shouldn't have worked at all because there was one ingredient missing, the petrified spider.
Suggested correction: The spell works because Winifred believes it is a petrified spider. It also works because she believes that Billy Butcherson was her lover; which he wasn't, as stated several times in the movie: in the flashback scene, Billy mentions it several times to Gilbert, and especially when Sarah tells Winifred that Billy was her (Sarah's) lover, to which Winifred replies that Sarah was just a fling; so the spell can work with incorrect material as long as Winifred, as the main witch, believes it.
Plot hole: When Cage and his wife and mates are going to the FBI safehouse the FBI agent shoots 2 baddies two separate times whilst Cage etc. are ascending the stairs, yet they don't hear the gunshots.
Plot hole: On Christmas morning, Karen went to the grocery store (open on Christmas!) where she donated $5,000 via credit card to the "Homeless Mother Shelter." Hours later, the $5,000 already showed up on Chris' laptop as deposited into the shelter's account. It takes days, not hours, for credit card transactions to be processed - especially if the transaction occurs on a holiday. (01:14:10 - 01:23:20)