Factual error: When Chigurh is in the gas station talking to the clerk, behind him on the shelf is a pack of Jack Link's beef jerky. The movie is set in 1980, but Jack Link's did not start selling beef jerky until 1985.
Factual error: At the very end of the movie, right before Javier Bardem is in the car accident, there is a shot out the driver's side window, past his face. In one of the driveways he is passing, a new Subaru Forester sits parked. The film is set in 1980.
Revealing mistake: In the scene where Llewellyn picks a cab to take in Del Rio, behind the cab that he takes is a cab with a rear license plate that reads J8R-725. Later in the story, at the crime scene, Llewellyn's wife drives up to the motel in El Paso in a cab with the same license plate number as the one in Del Rio.
Other mistake: After Chigurh kills the deputy at the beginning of the film, the next shot is an overhead, downward view of the sink and the killer's arms only, as he washes the blood from his cut wrists. Your attention is naturally focused on the handcuffs and bloody hands in this brief shot, but watch the extreme right edge of the screen. Chigurh has very dark, almost black hair, however, a small portion of the actor's head is seen twice during the shot, revealing light brown, or blond-like hair. The actor appears to be purposefully leaning away from the scene in the very beginning, but inadvertently leans forward during the washing action and the camera caught the hair. I believe the director used a hand model for this one shot.
Other mistake: When Chigurh first visits Moss' trailer on the Monday morning after finding his truck, the mail, including phone bill, is already inside the door. Chigurh uses the bill to call Carla Jean's mom, and when stymied, reviews the bill for additional clues as to Llewelyn's whereabouts. He sees a call made on June 2 to Del Rio and uses that to determine his next search location. Problem is, the Monday on which he found the bill is June 2, 1980. As well, the mail is on the floor behind the front door when Chigurh picks it up, however there is no mail slot in the front door.
Continuity mistake: When Sheriff Ed Tom Bell returns to the motel room where Llewellyn had been shot, his cruiser lights illuminate the room after he opens the door. We see the horizontal shadows cast by the police crime scene tape on the walls of the room, including the back wall,above the picture, as Bell walks through the room. After returning from searching the bathroom, however, there is no longer a tape shadow on the back wall, as he sits down on the bed. Note, that in the next camera angle shot of him turning his head to look down at the open vent, you can again see the shadows on the side wall, indicating the tape should still be intact and headlights still on.
Continuity mistake: In the motel room scene at The Del Rio Regal Motel, after Chigurh kills the Mexicans in his stocking feet, he removes his socks and tosses them into the bathroom. In the following shots, as he begins searching the room, we can see his bare feet. After he notices the vent above the doorway, however, the camera focuses downward on his hands, as he reaches into his pocket for change to use to unscrew the vent cover. The camera in that shot is in close-up focus on the hands, but, looking down toward the floor, you can make out the familiar reddish-brown, pointed toe boot on his right foot.
Continuity mistake: In the gas station scene, Chigurh places a crumpled candy wrapper on the counter as he is intimidating the owner, and the camera stays on the wrapper for a few seconds as it unwrinkles itself. Moments later, as Chigurh reveals the coin toss result, it is a completely different, blue and white wrapper.
Continuity mistake: After Chigurth escapes from the police department in the police cruiser, he pulls over the white 1977 Ford in order to "swap". As both cars pull to the shoulder of the road and stop, a long shadow is being cast onto the highway by the Ford. In the next shot, as Chigurth is walking up to the Ford, the shadow does not even reach the pavement, indicating that the second shot was filmed much closer to mid-day.
Revealing mistake: When Chigurh is preparing to blow up the car in front of the drugstore, he uses a piece of cloth as the fuse. He removes the gas cap, places a piece of cardboard over the opening, and lays the cloth on the cardboard. He then lights the cloth and walks into the drugstore. After the flames burn through the cardboard and reach the fumes from the gas tank, the car explodes. If you watch the burning cloth as he walks into the drugstore, you will notice that it never moves, not even when the car explodes. If the explosion had been real, the burning cloth would have been blown away from the car by the hot gases expanding out of the gas tank opening.
Continuity mistake: When Chigurh places his handcuffs around the police officer's neck to choke him, the handcuffs are more like manacles and contain 7 or 8 links between the cuffs. When he goes to wash the blood off of his wrists and drops the handcuffs in the sink, they are much smaller, containing only 3 links between the cuffs.
Continuity mistake: Chigurh is cut deeply on his wrists when choking the officer with his handcuffs at the beginning of the movie, but later when he is doctoring the wounds on his leg, his wrists are completely visible and there are no recent injuries.
Continuity mistake: In the scene where the two sheriffs inspect the burning car, Wendell puts his thumbs in his back pockets, where they remain for the next two shots from behind. Shots from the front, however, have Wendell's left hand in front, with his thumb through his belt.
Continuity mistake: During the gas station scene, Chigurh is continually eating from his bag of nuts. During the conversation between Chigurh and the attendant, as the camera cuts back and forth between them, Chigurh keeps eating a nut from behind, and then from the front, his hands are by his side and he eats a nut again. This occurs several times throughout the scene.
Factual error: Chigurh uses a captive bolt gun, which is supposed to explain why he feels no recoil. However. This only works if the gun is not pressed against something. If it's pressed against a target - like a lock in one case in the movie - he should feel an equal and opposite force to what is being experienced by his target: the mutual forces of action and reaction between two bodies are equal, opposite and collinear. The nature of the target is irrelevant: if it absorbs energy, as these examples do, there will be an equal and opposite reaction, which is recoil. The recoil of many of his uses should be significant enough to be very obviously visible.
Factual error: The international bridge was in 1980 staffed by US Customs agents who wore blue uniforms. The agent questioning Brolin's character is wearing Border Patrol green.
Factual error: As Sheriff Ed Tom Bell is driving up to The Desert Sands Motel, which is supposed to be located in El Paso, Texas, there is a sign on the right hand side which says "Route 66" - advertising a business on site. Route 66 did not go through El Paso - it was a few hundred miles to the north.
Other mistake: The case of money is in the complete opposite physical orientation when Moss retrieves it from the air duct in room 38. When Llewelyn Moss hides the money in the air duct from room 138, he pushes it to the end of the ductwork with the closet rod and then pushes it to the left with the top of the case and handle going in first and the bottom slightly sticking out. So the top of the case (with the handle) appears to be pointing left in looking at it from 138. When he pulls off the grill in room 38 the next day we can see the top and handle protruding on the right side of the air duct (handle facing left, as he peers into the ductwork). Since we know from the motel room map, that room 38 is directly behind 138, with common rear wall, the top of the case and handle should be facing the right, (from a visual perspective), as you look into the ductwork from room 38 - and it is not.