 The open country was filmed in the Cliffe marshes, and along the River Thames, supplemented with 200 imported Spanish palm trees and 100,000 plastic tropical plants from Hong Kong.Kubrick acquired four M41 tanks from a Belgian army colonel who was an admirer of the director's work, and Westland Wessex helicopters painted Marine green to represent Marine Corps Sikorsky H-34 Choctaw helicopters.Although the Wessex was a licensed derivative of the Sikorsky H-34, the Wessex substituted two gas turbine engines for the H-34's radial (piston) engine.