Factual error: Many of the main characters are using modern-day binoculars (black, plastic) throughout the entire movie.
Factual error: In the shot of the infield at the Saratoga racetrack several Canada geese are shown landing. However, the calls inserted on the soundtrack are the quacks of mallard ducks not the honks of Canada geese.
Continuity mistake: In the race for the $100,000 purse (that Rosemont wins), just after Seabiscuit takes the lead, there's a closeup of Seabiscuit's head and Pollard's right leg - Pollard is wearing the brace he made later in the movie after his leg was shattered. Obviously, the shot was taken from those filmed for the Santa Anita race later in the film.
Factual error: In the final race, Red Pollard is shown with a number 9 on his sleeve, indicating Seabiscuit's starting position. In fact, Seabiscuit had the number 1 starting position (this can be seen on historical footage).
Factual error: In the shot where Pimlico racetrack is shown and the dateline shows November 1, 1938, the Maryland flag is upside down. The black and gold squares should be at the inside top and they are not.
Factual error: Jockeys did not wear goggles and their skullcaps did not have chinstraps in the 1930's. Protective equipment for jockeys was practically non-existent during Seabiscuit's racing days.
Factual error: In the scene where Seabiscuit is weaned from his mother, the narrator says that he was six months old at the time. However, the foal used in the movie is less than one month old.
Deliberate mistake: In the final race of the film, Seabiscuit performs a flying lead change at the gallop while crossing the finish line, in the famous shot taken underneath his neck. Horses normally only switch their leads around turns while racing; it's something done to relieve pressure on the leading foot. From taking the shot over and over again, the horse playing Seabiscuit was probably tired out and a little tender and began to perform lead changes in other places in an attempt to be more comfortable.
Factual error: Two men are trying to start a John Deere Model D tractor, which backfires, startling the horse. The wrong sound effect is used; it sounds like a V8 engine being turned over by an electric starter. The tractor's flywheel, on the left side, is shown stationary. Turning the flywheel by hand is the usual starting procedure for a JD tractor of '30s vintage. For over 40 years John Deere tractors used a two-cylinder engine, which make a distinctive popping exhaust sound. The movie is right on one thing, JD tractors could backfire.
Factual error: Statements are made in the movie that War Admiral was "almost 18 hands" tall, when in reality, War Admiral was only 15.2 hands tall. War Admiral's nickname was "the giant killer." Seabiscuit stood 15 hands tall. Both horses were considered very small as racehorses.
Other mistake: In the hospital scene where Tom Smith, Mr. and Mrs. Howard and the groom are in the waiting room, it is mentioned that the evidence of the surgery taking time is noticeable by the light changing where Mr. Smith remains in the morning. In Seabiscuit, Mr. Howard, or Jeff Bridges, waits all night long to hear the results of the surgery, not Tom Smith.
Factual error: Pollard did not lose his sight in a fight, as the film suggests. He lost it when he was galloping a horse for exercise and a horse going in the opposite direction kicked up a clod of dirt that struck him at the base of skull and knocked out the cerebellum on his left lobe. (right side, left lobe).
Factual error: In the final race, one of the horse's saddle pad flips up in the wind and reveals a synthetic-type foam rubber lining. This was unavailable in 1938.
Revealing mistake: In the beginning scene, where the horse tamer is chasing the "mustangs", you can occasionally see the glint of a horseshoe on various "wild horses".
Factual error: During the times where Red is in the hospital, they show Red several times with a cotton blanket with a certain type of weaving they didn't use until the 1960's. In the 30's they were still using single weave blankets. Kind of hard to explain, but older nurses could tell you.
Factual error: When they are heading east to race with War Admiral, there is a scene at the Los Angeles Union Station. This is in 1938; the station was not opened until the following year.
Factual error: The license plates on the cars were dated TX 1937. I don't recall the movie ever happening in TX and they had not reached 1937 on the time line, yet.