Continuity mistake: During the whack-a-robot game, a big chunk of the broken robot lies on the counter, but it disappears a shot later.
Continuity mistake: When Grandma serves biscuit and orange juice to the kid, the yellow napkin on the table keeps changing positions between shots: from perpendicular to the table to skewed.
Other mistake: In this film, when they find the picture of Nancy (from the original Craft film), the image is of Nancy in the restroom of the original movie. If you watch the original film, the image that was used of Nancy shown in the new film would have taken place during the scene where Nancy, Bonnie, and Rochelle confront Sarah about wanting out of the coven. But during that scene, no cameras were in sight and nobody was taking pictures.
Continuity mistake: During the final fight at the very end of the film, pay attention to Millie's bloody nose. At first, there's an equal amount on either side. But a few seconds later, the suddenly less blood on the left side of her face and more blood on the right side.
Continuity mistake: Trevor is driving the Ecto-1 and complains that Podcast is breathing on him. We see Podcast very close to him. The shot cuts and Podcast is now further away.