The movie describes War Admiral as huge, close to 18 hands tall. In real life, War Admiral was about 15 hands tall, the same size as Seabiscuit.
Red Pollard affectionately calls Seabiscuit "Pops". This was the real nickname Pollard gave the horse. 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. The female horse, Pumpkin, would accompany him to all his races through out his racing career.
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.