In an early example of guerrilla film making, during the filming of Seven Days in May, John Frankenheimer filmed Martin Balsam being ferried out to the super carrier USS Kitty Hawk, berthed at Naval Air Station North Island in San Diego, without prior Defense Department permission.
Frankenheimer needed a commanding figure to play Vice-Admiral Farley C. Barnswell and asked his friend, well-known producer John Houseman to play him, to which he agreed, on condition that he have a fine bottle of wine (which is seen during the telephone scene), although he was uncredited for it. It was Houseman’s American acting debut, and he would not appear onscreen again until his Oscar-winning role in 1973’s The Paper Chase.
Frankenheimer also wanted a shot of Kirk Douglas entering the Pentagon, but could not get permission because of security considerations, so he rigged a movie camera in a parked station wagon to photograph Douglas walking up to the Pentagon. Douglas actually received salutes from military personnel inasmuch as he was wearing the uniform of a U.S. Marine Corps colonel. Several scenes, including one with nuns in the background, were shot inside Washington Dulles International Airport which had recently been built, and the production team were the first ever to film there. The alley and car park scene was shot in Hollywood, and other footage was shot in the Californian desert in 110 degree heat. A secret base and airstrip was specially built in the desert near Indio, California, and they borrowed an aircraft tail in one shot to make it look like a whole plane was off the picture.