In "Near Algodones" the words in the book reference the "First National Bank" but on the actual bank it says "First Federal Bank".
After Buster got shot in the head and took his hat off to check it, he then proceeded to pull out his mirror to look at his forehead. After he checks it, and falls, his hat disappears.
Immediately after Curly Joe (Clancy Brown) "commits suicide" by the hand (well, foot) of Buster Scruggs (Tim Blake Nelson) in the saloon at Frenchman's Gulch, a long shot from above reveals that all of the table's planks have chips or cards laid out on them in an orderly and undisturbed fashion, which would not have been possible after what had just occurred.
In the ballad of Buster Scruggs, after Surly Joe 'shoots himself', he teeters a moment, then falls back onto his chair, knocking the chair over as well, and the chair ends up on its back with Surly Joe lying on it. His left leg is hanging over the chair, leaning on the front left leg. The camera then cuts to a birds eye view of the whole saloon and Surly Joe is now lying off the chair, however the chair has turned 90° to what it was in the previous shot, it's now lying on its left side, instead of its back and Surly Joe's left leg is leaning on the rear right leg.
Buster's ears are crimped due to the position of his hat right before and directly after he is shot; after a quick cut-away to show that the other gunslinger drew first, his ears are no longer crimped even though the position of his hat never changed.
The owl in "All Gold Canyon" is not a great horned owl, native to the Americas, but rather a Bengal eagle owl which is restricted to Eurasia. This is presumably for the same reason that birds seen in a US film or television production are often of foreign origin: the Migratory Bird Treaty Act of 1918, which forbids using domestic birds species as animal actors.
In "The Girl Who Got Rattled", the wagons that were depicted were Conestoga Wagons. However, while they had been used as freight wagons in the East and South, they were seldom used on the trails to the West. They would have been too heavy for the trails. What likely was used is a Schooner, which would have been half the size of a Conestoga.
In "Meal Ticket," the Thespian recites the famous Shelley poem Ozymandias but repeatedly gets the first line wrong, saying "in an antique land" instead of "from an antique land."
The page shown at the beginning of "Meal Ticket" opens with duplicate letters: an ornamented 'T' and a regular capital 'T.'
In the The Gal That Got Rattled, Billy Knapp tells Alice about the 1872 donation land claim granting married couples arriving in the Oregon Territory 640 acres of undeveloped land (320 for single male citizens). This was actually the Donation Land Claim Act of 1850, which ended in 1855.
After the Cowboy in Near Algodones is about to get hanged for the first time, the horse wanders from its initial spot under the tree. If the rope around the Cowboy's neck is long enough to let the horse wander that far, he would have landed on his feet if the lawmen had had luck fulfilling the deed. Also, the rope changes angle in closeups vs. in landscape footage.
In All Gold Canyon, during the shooting of the prospector and subsequent struggle, six shots are fired. The assailant's revolver is a Colt Patterson model, an early percussion weapon with only a five-shot capacity.
During The Ballad of Buster Scruggs street duel at about 12 minutes, Buster fires 5 shots initially. The revolver's cylinder is visible from the front following the 5th shot, and all visible chambers are still loaded. None of the visible chambers should appear loaded.
In the Cantina, after Buster has shot all the hoodlums, he can see that the bartender is reaching for his gun up on the wall. He puts his gun hand behind his back and takes aim at the bartender, who's hands are on his rifle. A second passes, then Buster fires and shoots the bartender dead. The bullet goes right through the bartender and through the wall, allowing a ray of sunlight to shine right through the wall and the falling bartender. But as he's falling, the ray of sunlight twists in unison with his falling body and changes its direction of shine. It shouldn't. As he falls, no matter what position he is in, while falling, the ray should remain dead straight, when it emerges from his back.
In "All Gold Canyon", the prospector steals an owl's egg and fries it; but the egg seen frying is clearly an unfertilized hen's egg based on its size, bright yellow yolk and the lack of any owl embryo inside it.
On 1:04:19, the shadow of the man sitting by the hole falls into the hole, but he is lit from his right side, not his back, so you can see a second shadow to his left, out of the hole.
In meal ticket, the spacing of the 'stage' lamps differs, depending on whether we are looking from behind the actor, or looking at him from the front. Looking from the front, the lamps are more or less equally spaced, but when looked at from behind the actor the space between lamps two and three is much wider than between one and two and three and four.
The incident in the poker game makes no logical sense. The men at the table take offense to Buster not playing the quitting man's hand dealt (Aces and 8's AKA "dead man's hand"). They repeat "You seen em' you play em". Yet somehow, they let the original man who was already in the game walk away. That would be much more offensive for the original man to walk away from the hand he was dealt.
After crossing the desert on horseback, Buster Scruggs left the cantina without getting the drink of whiskey he came in for, even though there was nothing stopping him from helping himself to all he wanted.
In Meal Ticket, The Impresario is not named in the film credits yet there is a name (Thalia's Sedan) on the side and the front of the wagon.
In the chapter "All Gold Canyon," which takes place in or before the year 1873, the prospector sings "Mother Machree," a song published in 1910.
When the book "The Ballad of Buster Scruggs" is first opened, the copyright date is shown as 1871, so none of its stories could have happened later than that year. This makes it difficult to understand why Buster would refuse to play the poker hand left behind by the player who dropped out--two pair, aces and eights, is not that bad a hand. Of course, it's also the notorious "dead man's hand" held by Wild Bill Hickok when he was fatally shot--but there's no way Buster could have known that. Wild Bill died in 1876--five years (at least) after Buster picked up the cards.
According to Merriam-Webster, the word "crackpot" was not used until the 1880s, by which time the migration along the Oregon Trail was replaced by railroads.
The guitar Buster is playing is a Recording King which wasn't available until the 1930s.
The Outlaw's holster is stamped Carrico's Edna, KS. Carrico's is a Leatherworks that has only been in business since 1992.
The Impresario has been swindled. He needs the equipment to make the counting chicken act to work. The act works on a food cue; the guy who sold him the chicken will just train another one. he killed the "Wingless Thrush" for nothing.
In "Meal Ticket," the Thespian recites the Shelley poem Ozymandias but repeatedly gets the first line wrong, saying "I met a traveller in an antique land" instead of "from an antique land."
(Possibly intentional) In "The Ballad of Buster Scruggs" segment, Buster claims that the town of Frenchman's Gulch is new to him. Yet, only a few moments later he sings about Surly Joe stepping into the saloon the previous April.