Continuity mistake: When Walt is talking to the Denver detective, he opens the door to go inside and then the detective says they found the man who killed Walt's wife. Walt stands there, holding the door open still. When the camera angle changes, he's no longer holding the door open and goes to open the door again.
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: When Walt and Vic are driving during the day, the sun changes constantly when the shot angle changes from each character.
Dogs, Horses and Indians - S1-E9
Continuity mistake: When Walt is chasing Dullknife, they're on a two-lane road divided by a single dashed yellow line. However in some of the close up shots, it's now two yellow lines (a solid yellow line with a dashed yellow line). This is before they get to the road block.
The Cancer - S1-E4
Continuity mistake: When Walt walks up to his house, Henry is standing there with the pizza and Lizzie's note in his hand and the note is unfolded. In the next shot, Henry unfolds the note.
Other mistake: In the opening shot of the dead girl, there's a $1 bill next to her face. However, the picture on the $1 is not George Washington.
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.
Revealing mistake: Vic and Walt are walking toward the crime scene in the snow, while Vic is complaining about the job. In a high angle, you can see two tracks in the snow ahead of the actors where they practiced the scene before.