While performing surveillance on the roof, Sergeant Carter is using a Honeywell Pentax SLR 35mm film camera with telephoto lens. Although he is manually winding film, the film sprocket is not moving - suggesting there is no film in the camera.
When the Flying Squad are at Tim Cook's caravan about to nick him, Regan tells Hargreaves to position himself by the tree on the right, when Regan does so, he is actually pointing to the tree on the left.