Other mistake: The window in which Ben climbs in at Reverend Frank's house seems too narrow when viewed from the outside. But in the next shot inside the house, the window is wider.
Plot hole: Reverend Frank reveals that he once married an immigrant from his congregation so that she could stay in the country after her application for asylum was rejected. No immigration official would ever have believed such a marriage (to a priest!) to be genuine and her application of leave to stay would have been rejected.