The racing scenes in this movie are all re-creations except one: the Preakness, which is seen on an old television in the Tweedy family den. That's historical footage of the actual race.
In the Belmont Stakes, Secretariat's winning margin (31 lengths) and winning time (2:24) still stand after 37 years.
The horse used in most of the close-ups was named "Longshot". Although "Trolley Boy" looked more like Secretariat overall, Longshot was deemed more "close-up friendly".
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.
Otto Thorwarth, Secretariat's jockey, is a real jockey who was born in Arkansas, but spent his early life in Canada. He had to work to lose his Canadian accent for the film. The other jockeys are also real jockeys; there was much riding to be done, and actors couldn't get the horses to perform as required, gauging the distances needed for the various wins, places, and shows. Director Randall Wallace says the distances are accurate to within 1/2 length in each re-creation.
Michael Mills: The golfer next to John Malkovich at the driving range is the head of the make-up department for the film.