Other mistake: Throughout most of the film, Mattie Ross' gun is correctly shown to be a Colt's Dragoon .44 caliber revolver. However, in the scene where Tom Chaney is looking down at her from the top of the well into which she had fallen, the gun in his hand is a Colt's Model 1860 Army. Presumably, when he, too falls into the well after being shot by Marshall Cogburn, the gun goes with him. When Cogburn retrieves the weapon before helping Mattie out of the pit, the gun is once more a Colt's Dragoon.
Ned Pepper: What's your intention? Do you think one on four is a dogfall?
Rooster Cogburn: I mean to kill you in one minute, Ned. Or see you hanged in Fort Smith at Judge Parker's convenience. Which'll it be?
Ned Pepper: I call that bold talk for a one-eyed fat man!
Rooster Cogburn: Fill your hands, you son of a bitch!
Col. G. Stonehill: I will pay a total of two hundred dollars to your father's estate when I have in my hand a letter absolving me of all liability from the beginning of the world to date!