The chalk tunnels used are over a mile long. They begin in an English cottage garden and spread out under most of the surrounding village. The cottage owner Andy Meecham appears in the film as a Tunnels Nazi.
The 1940s house used in the interrogation scenes is the home of director Andy Green. All the furniture and props are his.
The secretary in the interrogation scenes is the make up and effects supervisor Helen Lake. She is responsible for all the blood and guts in the film.