Continuity: The position of Lon's arm changes as he as Hud share a drink and talk about a girl after the pig contest.
Continuity: After Hud hits the guy at the bar, he takes a swig from his bottle-in-bag, which is on the bar, but which he had left at the table.
Revealing mistakes: As Lon exits diner in opening scene, radio announcer says time is "6:26" a.m. - but lack of long shadows clearly identifies time as near noon.
Crew or equipment visible: When the vet first comes and is talking to them all about possible causes of the cow death, the wind comes up and causes one of the mylar reflectors to wobble, creating a flash in the scene like someone fired a camera.
Continuity: When Hud leaves the married woman's house, he puts on his boots and his pants are tucked into the boots. The next time you see him, his pants are outside of his boots.
Crew or equipment visible: In the first scene, you can see the cameramen and tripod of the cameras in the window of the store.