Anton Chigurh's weapon is a captive bolt pistol or a cattle gun, used to kill cows before slaughter. The tank contains pressurized air, which propels a pointed bolt. The bolt penetrates and then retracts automatically.
The Coen brothers got the idea for Chigurh's hair from a book Tommy Lee Jones had. It featured a 1979 photo of a man sitting in the bar of a brothel with very similar haircut and clothes to what Chigurh ended up wearing in the movie. Legendary Oscar-winning hairstylist Paul LeBlanc designed the hairdo. The Coens instructed him to create a "strange and unsettling" hairstyle. LeBlanc based it on the mop tops of the British warriors in the medieval Crusades as well as the haircuts of the 1960s. Javier Bardem told LeBlanc every morning when he finished the hair that it helped him to get into character. Bardem famously feared he was "not going to get laid for three months" because of his haircut.
The movie doesn't explain why Chigurh gets arrested at the beginning of the movie. In the book Chigurh tells Wells that he let himself get arrested for killing a man who had insulted him in a bar: "An hour later I was pulled over by a sheriff's deputy outside of Sonora Texas and I let him take me into town with handcuffs. I'm not sure why I did this but I think I wanted to see if I could extricate myself by an act of will. Because I believe that one can. That such a thing is possible. But it was a foolish thing to do. A vain thing to do. Do you understand?"
When writer Cormac McCarthy visited the set, the actors inquired about Chigurh's background. Where does he come from, what is the etymology of his name, what mythological character is he based on? McCarthy goes, "I just thought it was a cool name."
As Chigurh enters the pharmacy, a Wells Fargo bank is visible. Wells Fargo didn't operate in Texas in 1980.
When Man at Chair (accountant) asks "Are you going to shoot me?" and Chigurh replies "That depends. Do you see me?" the script calls for Man at Chair to say "No."