 The nuclear bunker that James Cromwell and Morgan Freeman walk into  at the beginning of the movie is a real nuclear bunker. The scene  was shot at a real Canadian nuclear bunker in Carp, Ontario. This  bunker was designated as the one that members of the Canadian  government, including the Prime Minister, would be housed in during  a nuclear attack. The bunker was in operation from 1961 until the  mid 1980s, and was known as the "Diefenbunker" in honor of former  Prime Minister John Diefenbaker, who was PM during its initial  construction.