 The museum ship stood in for most of the "Missouri" sequences, and the USS "Drum" portrayed the North Korean submarine.The film makes extensive use of the Introvision process, a variation of front projection that allows realistic three-dimensional interaction of foreground characters with projected backgrounds without the heavy cost of traditional bluescreen effects.The technique was also used in the films "Outland", "Megaforce", "Army of Darkness" and Andrew Davis' later film, "The Fugitive".