To help Eurocom authentically recreate the environments of the film, the film makers provided Eurocom with original production material, including concept drawings, blueprints, and photographs of the film's sets. Although the game closely follows the plot of the film, the developers added elements to help the game design. For example, the London Underground level, where the player must rescue several hostages, is not part of the film. However, the boat chase scene is not playable in the game due to limitations in the Nintendo 64 cartridge size. According to the game's producer Bill Beacham, vehicle-based gameplay would require the creation of a separate engine that would possibly compromise the game's base first-person engine. The characters' faces were digitised from the film's actors, but impersonators provided voiced dialogue. One exception was English actor John Cleese, who reprised his role as R.