I had the pleasure of attending the premier showing of that movie in 1980. Charlton Heston, his son Fraser and his wife, and Victoria Racimo (who played the female lead), all spent three days at the 1980 NMLRA/NAPR Joint Rendezvous in La Veta, Colorado. Fraser Heston wrote the script for the film. Fraser and Charleton both took part in a rifle match at the rendezvous where the targets were raw eggs. Victoria wanted to learn to throw a tomahawk correctly and did so. Brian Keith was involved with another project in Hawaii at the time and couldn't attend. Columbia Pictures rented the drive-in theater in La Veta and that's where the movie was shown for the first time. Many of the non- speaking parts in the movie, including most of the people in the rendezvous scenes, were not professional actors but buckskinners who had been invited to participate as unpaid "extras" and Columbia Pictures provided the food and beverages while that part of the filming took place. Showing the movie to buckskinners first was part of the deal.