Continuity mistake: In the scene where Branch and his father are target shooting, right before Branch confronts his father about having Longmire's wife murdered, he takes out his ear plugs. Then when his father triggers the trap machine Branch turns his head and you see an ear plug in his ear.
Continuity mistake: Longmire is taping prisoner photos to the wall. When looking at the last photo, the tape is in the middle of the paper. When he puts it on the wall, the tape is on the right side of the paper. When the photo is in the background, the tape is on the left side.
Continuity mistake: Walt shows up to the first crime scene after visiting his daughter. He and Vic begin to discuss the girl. In the first shot of the girl, she is facing the camera and has her eyes closed. The very next shot of her, her head has moved and her eyes are open.
Continuity mistake: Vic and Walt are driving and Vic is talking about how she could be a stripper. This scene must have been filmed at two different times of the day as the sun is on Walt's side for his scene, and Vic's side for hers. Look at the shadows and sun glare in the shots.