When Nick and Sara remove bricks to get into the chimney, they remove six bricks. But when the camera view changes to inside the chimney looking out, there are only 4 bricks removed.
When Sara lifts prints from the brick of the chimney, they are a clean set of prints, only the finger prints. Bricks are a textured surface and as such, there would be breaks in the prints, not complete and clean, where the texture is apparent in the prints.