Factual error: Several times firearms registration is mentioned, but Wyoming has basically no gun laws. No registration is required, and no concealed carry permits are required.
Continuity mistake: Walt and Vic are in the compost heap digging around. Vic is without gloves while digging and when drinking the offered drink. She then resumes digging around with rubber gloves suddenly on her hands.
Unquiet Mind - S2-E1
Character mistake: When Walt is coming up to Mars cabin he hears a gun shot, he then re cocks his gun ejecting a live round, since he has not yet fired it. (00:20:30)
Unquiet Mind - S2-E1
Continuity mistake: During the day when Walt is following the Snowcat, he hears a gunshot and puts his backpack down to pull out his binoculars. He doesn't have anything covering his mouth, but in the next shot his scarf is covering his mouth. And in the previous shot we see both his hands, so he doesn't have one free to pull it up.
Death Came in Like Thunder - S2-E3
Visible crew/equipment: In the jail when Sal starts throwing around furniture you can see the camera man's arm.
Answer: Chance.