The title refers to the biblical fall from innocence. In Sweden, however, the title was translated as "Höstlegender" meaning Legends of the (season) Fall (as in autumn). Similarly, in South Korea, the title was "Gaeul-ui jeonseol" interpreting "the fall" as the autumn season.
This movie was originally to be filmed in Winnipeg, Manitoba (Canada), but the city officials refused to remove several trees (which would have been replaced after the end of filming).
The book from which Colonel Ludlow is reading the night the boys announce they're going to war is the short story "Rikki-Tikki-Tavi" by Rudyard Kipling in "The Jungle Book," volume two.
Calgary was chosen as the main filming location because of its dry weather. Naturally, once the production started there, they were met with record rainfalls.
The brothers enlisted in the Canadian Army and appear to have served in the 10th Battalion Canadian Expeditionary Force by the badges on their uniforms. The 10th Battalion was formed from the 103rd Regiment (Calgary Rifles) which was later known as the The Calgary Regiment.
In Legends of the Fall (1994), Brad Pitt and Julia Ormond play star-crossed lovers of about the same ages. In The Curious Case of Benjamin Button, Julia Ormond plays Brad Pitt's daughter.