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.
Answer: Something he made up.