The film depicts Jim Thorpe as being married once, and having had one child who died young. In fact, he was married a total of three times and had seven other surviving children.
The film is so riddled with errors and fabrications that it would be difficult to list them all - for example, the story of the games against Penn and Harvard - Carlisle did defeat both on several occasions, but never in the manner or by the scores shown. But most egregious is the portrayal of Glenn 'Pop' Warner as an avuncular father figure to Thorpe. In truth, Warner abandoned Thorpe to save his own career after Thorpe's non-amateur status was discovered following his Olympic triumph, something that Warner almost surely was aware of.
According to the Burt Lancaster biography by Kate Buford, his son Billy contracted polio during the shooting of the film, at the same time that Lancaster had to act in the scenes where his son in the movie died of influenza.