Incorrectly Regarded As Error: When Cooper's character is shooting DeSilva's character in the end of the movie it is often thought that the second gunshot that is heard is a mistake but it actually comes from DeSilva's gun as he falls to the floor after receiving the first gunshot from Cooper. The smoke from DeSilva's gun is visible before he falls.
During the waterfalls chase scene, after their fall from the canoe, Abby and Chris make their way towards safety. Abby is wearing hard green and white dress shoes, but moments later she is wearing soft dark gray moccasins.
During the rapids chase six Senecas occupy each of two long canoes. Later in the chase the canoes are shorter and hold only three men apiece.
Near the end of the movie, when Gary Cooper is shooting Howard Da Silva in the barn, he shoots him, then when he draws his other gun, another shot is heard. This kills Da Silva, even though Cooper is only holding the gun, not pulling the trigger.
When going over the waterfall, support wires can be seen on the actors.
When the Indian is being attacked while Gary Cooper is in the tree and Cooper's character throws a knife at him, as he falls to the ground on his back you see the knife protruding from below his belt line, from an angle as the knife was just stuck into the top of his trousers.
Although working as a slave, Abby has perfectly applied makeup and lipstick.
Dan McCoy's comment, "Now that's a good Indian", about the native killed by Holden is based on the quote attributed to General Philip Henry Sheridan, "The only good Indians I ever saw were dead." Sherdan is supposed to have said this in 1869.
The film ends with a close-up of an engraving mounted on a door reading "Where Liberty is, There is my country - Benjamin Franklin." Franklin was said to have written these words in a letter dated March 14,1783, twenty years after the events depicted in this film.
John Fraser talks about steel production from the iron and coal to be found in the Ohio Valley area at 40:00 minutes while talking about Pittsburgh. Though steel was known in 1780 it was almost another century until large scale steel production occurred in the United States.