While the movie describes War Admiral as being a huge horse close to eighteen hands tall, the real-life War Admiral was well known for being one of the smallest sons of Man o' War. War Admiral was actually the same size as Seabiscuit, which was approximately fifteen hands tall.
When Red Pollard tells George Woolf how to ride Seabiscuit, he says, "Show him the stick at the quarter pole, and he'll give you a whole new gear." To show the stick means to bring the whip, or crop, up close to the horse's eye, on one side, with the suggestion that the next move might be a whipping along the flank. The crop is not meant to hurt the horse, only to say, "Okay, NOW is the time to really move!" Many horses run faster if slapped; others simply freeze and stop running. To show the stick, then, is only a suggestion, and it will make most horses shift into higher gear, if they still have energy left to run for the win. (And animal lovers should note: the horse crop is not used to hurt the horse, only to excite it with adrenaline or (worst case) fear. A jockey who draws blood is likely to be penalized up to the point of losing his or her license, which means no more employment.)
A contraption called Equicizer was used to film the close-up action. It resembled a hobby horse. It was a mechanical horse that had springs, a wooden head and a carpet body. It was affectionately called SS Seabiscuit. In reality, it was a 12 ft by 20 ft rolling platform with a steering wheel in the rear and front. It simulated the rolling action of a running horse and yet it ran on rails around the track. It was powered by a 454 Chevy engine and could go at a speed of 40-50 mph.
Jockey Red Pollard is shown to keep his weight down by starving to 115 pounds. This was because Seabiscuit, when young and already small, had to run in what are called handicap races. The "handicap" is an added weight that is assigned to each horse according to its past races and its predicted ability to run against horses who weigh more or less than it does. Many jockeys will starve themselves so that their horse will carry as little weight as possible: that is: their own weight plus the lead weights which are laid into the saddle of the running horses. Red Pollard, at 5'7", raced against professionals who were 5'3" - but many jockeys will do almost anything if they love racing enough and are daring enough to risk their bodies.
When trainer Tom Smith tries to bring a goat into Seabiscuit's stall, he is absolutely right in saying that many horses feel better if they have company. (Most mammals who live with humans do.) It has been a fairly common practice to partner a horse with a goat in a stall. It is also alleged that the saying "to get one's goat" came from the practice of stealing a goat from a rival race horse's stall the night before a big race, so that the horse would be upset. This etymology is possible but has never been fully supported. (That a horse would neatly kick a goat out of its stall is, of course, fanciful.)
Most of the audience at the Pimlico Race with War Admiral were blow-up mannequins with masks as faces, long sleeve T-Shirts with painted on suits, and plastic hats (which were provided to all of the unpaid extras).
In the scenes filmed at Santa Anita racetrack you can see a statue of a horse by the paddock. This statue is a memorial to Seabiscuit that exists at Santa Anita. Another statue stands approximately 100 yards away; this is a tribute to George Woolf, Gary Stevens' character in the film.
The Seabiscuit/War Admiral race originally held at Pimlico race track was actually filmed on location at Keeneland race track in Lexington, Kentucky. The track, as well as some of the surrounding area, had to take on some minor cosmetic changes in order to accurately reflect the time period.
Although the film doesn't mention it Seabiscuit and War Admiral were supposed to race in June of 1938 in the Massachusetts Handicap. Seabiscuit was scratched due to "fevered legs". War Admiral finished 4th marking the first time he finished out of the money.
Red Pollard (Toby Macguire) affectionately calls Seabiscuit "Pops". This was the real nickname Pollard gave the horse since Seabiscuit was considered "old" during his time as a major thoroughbred racer.
The companions Seabiscuit is given to calm him down were actually used in real life. The stray dog was named Pocatell, and the female horse, Pumpkin, would accompany him to all his races through out his racing career.
Chris Cooper had to be aged for his character to look the part. Because he was over 25 years younger than his character, Cooper's hair was whitened and his hairline was shaved back to show a widow's peak hairline. Cooper, being significantly younger than Jeff Bridges, was made to appear older than the actor he played opposite.
When trainers and jockeys refer to a horse having "a great heart" or "a noble heart," they do not mean courage, as we would say about a human. They mean that it has a competitive nature. A horse that has more stamina than speed would also be described as having a great heart (though perhaps more often in steeple-chasing than in flat racing).
Director Gary Ross's six-year-old son Jack told him that John Schwartzman should be the cinematographer of this film. The boy had just seen The Rookie (2002), Schwartzman's previous film, and loved the way it looked.
While never stated in the movie, War Admiral and Seabiscuit were in he same bloodline and rather closely related. A stallion named Fair Play sired Man o' War and Man o' War sired War Admiral and Hard Tack. Hard Tack was Seabiscuit's father making Seabiscuit War Admiral's nephew.
Ex-racing driver Allan Padelford specially designed the MTV insert cars - a Mobile Technocrane Vehicle to allow filmmakers to shoot insert shots for horse race sequences. It run up to 45 mph and weighs at 28 thousand pounds. The car can fit a 30ft Technocrane dolly at the back and Wescam XR head at front. Another one was designed specifically two fit in two animatronic horses.
It was not said in the movie that Seabiscuit and War Admiral were in the same bloodline. Fair Play sired Man o' War who sired Hard Tack and War Admiral. Hard Tack sired Seabiscuit making him the nephew of War Admiral.