In the confrontation between Miss Goodnight (Katherine Hepburn) and Judge Parker (John McIntire) in the closing moments of the film, he acts as though he has never heard Cogburn (John Wayne) called by his true name, Reuben. However, in the courtroom scene at the beginning of "True Grit," the same character (with James Westerfield in the role) is sitting at the bench as the bailiff (Dennis McMullen) clearly calls "Marshal Reuben J. Cogburn" to the stand.
Katharine Hepburn (who was 68 at the time of the filming) is clearly wearing makeup throughout the film. Not only this not be likely for time period, it definitely would not socially appropriate for a "spinster" as the character she was portraying is supposed to be.
The cases of nitroglycerin at issue in the movie are labeled "Hercules Nitroglycerin." However, the Hercules Powder Company, which did produce nitroglycerin, did not come into existence until 1912, a result of an antitrust action brought against E.I. du Pont. As the movie plainly takes place in the late 1800s, Hercules could not have produced the nitroglycerin at issue.
Just before Rooster sends Wolf out to keep watch on the big flat rock, he talks about Chen Lee and General Sterling Price. When he says "General Sterling Price" in that scene, his lips don't match the words being said. You can also hear the audio change back and forth.
After the initial gunfight, Rooster Cogburn is bringing all the dead men back to the town. The deputy sheriff is lying dead over the saddle on the first horse behind Rooster. If you watch you will see him lift his head independent of the horse's movement and then moments later he slumps down again to play dead.
During the last leg of the raft scene after Rooster has put the boxes of rifles into the water, his 1892 Winchester changes to a Spanish knockoff . The loading gate on the receiver is forward almost to the wooden fore-arm as opposed to a third of the way back on a Winchester.
When Rooster, Wolf, and Eula are riding through the woods to catch the gang, Eula begins with
the white shawl over her hat, then it is missing, then appears again, and then is missing when they finally stop.
When Rooster Cogburn is fending off the pursuing bandits, he fires up at them on a rocky hillside from below on the river on a raft with a Gatling gun. In one scene as he fires away with the Gatling, the camera angle is from above both the bandits and Cogburn and shows multiple bullets hitting the rocks just around the bandits feet which are on a flat ledge jutting out on the hill and is an obviously impossible spot to hit due to the location of the Gatling gun and the angle of the ledge.
Breed (Anthony Zerbe) is clearly shown taking three bottles of nitroglycerin from a crate, and you can see he is holding three bottles as he rides down the hill. A wide shot shows the first two bottles being thrown, then a closer shot of the third bottle being thrown, but in that shot you can see he is holding another bottle of nitroglycerin in his non-throwing hand, which would make four bottles total.
When they are on the raft at night, Eula and Rooster are talking. When the camera is on Rooster, we see the background moving as if he is facing downstream. Similarly, when Eula is in shot, she appears to moving downstream. As they are facing each other, it is impossible for them to be both facing downstream.
At the beginning of the movie Rooster's deputy gets shot along with four desperadoes - three at the table and one hiding in the corner. Rooster then rides back to town with the deputy's body and only three of the desperadoes. What happened to the fourth desperado's body?
The movie is set in Arkansas (per the court scene immediately following the opening), but features mountains, a river canyon, and other natural features totally unlike anything in Arkansas. Not surprisingly, these features are found in Oregon, where the movie was shot.
Although the film begins in Arkansas, much of it takes place in the "Indian Territories" which was the pre-statehood term for Oklahoma. Most of Oklahoma is either flat plains or rollings hills. However, the mountains and canyons shown in the film clearly do not exist in Oklahoma.
When Rooster tells Eula the quote, "When a soul needs reviving, thou shalt reach for help," she asks for the book and verse, to which he responds, "Rooster Cogburn, 1880." However, True Grit (1969) took place in 1880 as evidenced by the tombstone for Mattie Ross's father at the end of that film. In this film, it is obvious that the events cannot be happening in the same year, mostly based on Rooster's grayer hair and higher number of kills as enumerated in court.
The raft is stopped by a rope stretched across the river. It is obvious that the rope didn't stop the raft and when Rooster cuts the rope it is not taut from the tension of holding the raft but just laying in the water and obviously not holding the raft at all.
When the pack of four horses carrying dead men draped across the saddles crosses the bridge at the beginning of the movie, the next-to-last dead man is holding his arm up at an angle from where it should be, and he drops his arm at the last second before the camera moves on.
When Rooster gets the Pepperbox out to give to Wolf, he says "I got me a 22 Pepperbox." The bore in the end of the barrel is to big for a 22 cal, it is more like a 36 cal, which was the most common caliber used.
When Hawk shoots the Rev. Goodnight at close range, his revolver is pointed to the left of Rev. Goodnight's head and the black powder muzzle blast can be seen as it goes by him, proving the gun was not aimed at him.