Famous Paint Horses: What Made Hidalgo Special?

Hidalgo is said to be an epic biographical western film made in 2004, based on an American distance and dispatch rider Frank Hopkins and his mustang Hidalgo. The film takes place in Arabia in 1891 and depicts how Hopkins was invited to participate in a horse race known as, the “Ocean of Fire” that consisted of a 3,000 miles dash across the Arabian Peninsula.  
Five American Paint Horses registered with the Paint Horses Association played Hidalgo and an Arabian show horse owned by “Black Silver Arabians stables,” in Burson, California, called TC Bey Cedar, played the part of Al-Hattal. Hidalgo was a mixed-breed wild horse known as a mustang brought to the Americas at the same time the Spaniards joined the New World. In the movie, these mixed breeds, according to the horseracing world, were considered unworthy of even sharing the road with purebred horses per the sleek Arabians. 
The last scene with the horses took place in Browning, Montana where they used 550 different horses to film the scene. Moreover, because all the horses had different owners and needed to be identified some way to tell them apart, they branded their hooves.  
This was supposedly a true story yet, some claims made were found to be false as researchers found Hopkins didn’t actually live such a western cowboy lifestyle, but more of urban life.