When the creepy man stands on the wall above Larry's bed, in close-ups Larry has his hands spread apart, but in long shots they are clasped together.
When Aunt Kate slides down the banister of the grand stairs in the foyer, they creak as if wood, however the banisters are clearly marble. One may, however, assume this to be artistic licence for the benefit of humour.
When Larry and Vicki are driving to the castle/mansion, a road sign is visible that shows the road curving (dog leg). The sign is on the wrong side of the street and does not match the curve of the road.