Richard Jordan later admitted he decided to overplay his part because he thought the movie was going to flop, and if anybody paid to see it then it would only be for the two stars. He also said he felt that Katharine Hepburn was about to die at any minute - ironically, she outlived him by a decade.

Katharine Hepburn was bemused by co-star John Wayne's tendency to argue with everybody, especially the director, during filming. At the party to celebrate the last day of filming she told him, "I'm glad I didn't know you when you had two lungs, you must have been a real bastard. Losing a hip has mellowed me, but you!"

Director Stuart Millar insisted on so many takes that eventually John Wayne snapped, "God damn it Stuart, there's only so many times we can say these awful lines before they stop making any sense at all."

John Wayne found making the film to be very difficult, particularly since he had just finished a grueling shoot on Brannigan (1975) and recovered from pneumonia.

Jon Lormer, who plays Katharine Hepburn's father, was only one year older than her.

Continuity

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.

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.

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.

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.

As Rooster, Eula, and Wolf ride quickly through the woods after first spotting Hawk's gang, Rooster wears a coat, then just a shirt in the long shot, and the coat again.



Factual errors

In one scene, the Indian boy, Wolf, asks Rooster Cogburn if he ever ran into Billy the Kid or Jesse James, which Cogburn denied; however, Cogburn served with Quantrill's Raiders, a pro-Confederate guerrilla group in the Civil War, whose members included a then-teenage Jesse James--making it quite likely that Cogburn would've met him.

When Breed is shooting into the dirt toward Bula she recites the 23rd psalm however she skips a line, "thou anointest my head with oil".

Rooster has Eula fire a Gatling gun. The rounds go off three times faster than any Gatling gun could be cranked.



Revealing mistakes

The stunt doubles for John Wayne, Katharine Hepburn and Richard Romancito are very obvious in the riverboat scenes.

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 lying in the water and obviously not holding the raft at all.

When Hawk shoots Breed, he accuses Breed of only fighting Rooster Cogburn with one bullet, since Breed had only used one bullet to shoot Luke in the back as Luke was fixing to shoot Rooster Cogburn. However, there was no way for Hawk to know for a fact if the current load in the gun was the same as the load right after the shootout (i.e. Breed could have reloaded and forgot a shell, reloaded and shot another one, reloaded multiple times, etc.), Hawk never asked to see Breed's gun belt so he couldn't have known for a fact how many shells had been used.

In the first attack on Rooster and company three small bottles of nitro are thrown like hand grenades. The explosions are noticeably distant from where the bottles land.

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.



Miscellaneous

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. A logical explanation could be that Rooster did say these words in 1880 and has had occasion to repeat them now and then.



Anachronisms

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.

Much of the clothing in the film is not period correct. Several of the men's coats were clearly sewn by machine and not by hand. And a number of the hats worn were clearly not in style in the 1880s.

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.



Audio/visual unsynchronized

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.



Errors in geography

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 rolling hills. However, the mountains and canyons shown in the film clearly do not exist in Oklahoma.



Plot holes

Eula looks the same age as her father.



Character error

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.

When Rooster first meets Eula and Wolf, he refers to his pistol as a Navy Colt but it is clearly a Colt Single Action Army (Peacemaker).