The Castle used on location in this film was Manorbier Castle, Pembrokeshire, Wales, Great Britain; (but not the shots of the lone turret). Manorbier Castle was also used as location for the BBC adaptation of CS Lewis' "Prince Caspian"
Manorbier Castle in Tenby, Wales, which was used for many of the shots of the Mortmain family's castle, had a moat that had not been used for many years. For the shots of Cassandra and Neil swimming in the moat, large amounts of clay were brought in to make the moat watertight. It was then filled from tankers of water brought from elsewhere, because the local water supply could not supply the large amount needed.