In 1971, he and fellow stuntmen Glenn Wilder and Ronnie Rondell formed Stunts Unlimited. Norris is also credited as the stunt coordinator and listed amongst the stuntmen. The actors trained alongside the stuntmen, and even Snyder joined in. However, Talalay wanted real actors rather than stuntmen in suits playing the roles. Aerial stuntmen B. J. Worth and Jake Lombard performed the pre-credits parachute jump. Several scenes had the monster portrayed by stuntmen in suits. A team of eight top Chinese stuntmen and coordinators out of Hong Kong were hired. The scene took a total of 88 skydives by the stuntmen to be completed. The stuntmen were filmed later, added by optical effects. The opening war scene was filmed over three weeks and required fifty stuntmen. For the safety of the stuntmen, many props were made of foam rubber. They were joined by the Buftea film studio stuntmen and many volunteers. Many of the film's stuntmen were sent to the hospital after being gored by bulls. The stuntmen involved in the scene were actually running for their lives. The scene required 145 extras, 38 stuntmen and $90,000.