Not only did Secretariat set the record for the fastest time at the Kentucky Derby (1:59 2/5), each of his quarter-mile splits were faster than the preceding one, which means he was still accelerating at the end of the race. His split times were: 25 1/5, 24, 23 4/5, 23 2/5, and 23.
The words that Diane Lane speaks at the end of the film are from the book of Job, Chapter 39, when God is describing horses. Verse 22: "It laughs at fear, afraid of nothing; it does not shy away from the sword." Verse 24: "In frenzied excitement it eats up the ground; it cannot stand still when the trumpet sounds."
Secretariat's time in the Kentucky Derby is still the record for that race (1:59 2/5). Only one other horse has won it in under two minutes (2001, Monarchos, 1:59.97). Sham, second to Secretariat, may have run it in under two minutes, but there is no official time for him.
Five horses played the part of Secretariat. "Trolley Boy", the principle horse used was selected by Penny Chenery in a Secretariat look-alike contest in Kentucky, and even walked the Red Carpet at the film premiere in Hollywood. The five horses, four thoroughbreds and a quarter horse were made up with special makeup to replicate the three "white socks", facial stripe and star.
Some of the closeup shots of the racing horses were achieved by attaching lightweight digital cameras to sticks and positioning them close to the horses as they galloped around the track. The horses got used to it, but the jockeys were sometimes startled by them.
The Triple Crown trophy seen after the 3rd race is the actual trophy, not a replica. It was loaned to the production by the Kentucky Derby Museum, and was human-accompanied on the trip from museum to film set and back.
Otto Thorwarth, Secretariat's jockey, is a real jockey who was born in Arkansas, but spent his early life in Canada and picked up the accent. He had to work to lose it for the film. (The other jockeys are also real jockeys, there was much riding to be done and everyone knew actors couldn't get the horses to perform as required, gauging the distances needed for the various wins, places, and shows. The director says the distances are accurate to within 1/2 length in each recreation.
The scene where Penny Chenery can't make it to Kate's play, listens on the phone, and collapses in sobs on the hotel bed was done in one take. Randall Wallace said he was so emotionally involved in the scene he couldn't have shot another one.