You see Gabbie is holding the bedding as Harriet is talking about the ghost horse, in the next shot she isn't holding the bedding and her hands are together.
When they are reversing away from the mansion, no white back up lights are visible on the tail lights of the car.
Later on in the movie, a secret seance room is discovered via blueprints and the room has a domed skylight. The same domed skylight is visible in the backyard, even more so when Ben talks to Travis in the backyard.
When they enter the Seance Room, someone remarks that no one's been in there for centuries, ignoring the very obvious bank of security monitors directly in front of them.