Visible crew/equipment: In the flashback scene where Jesse breaks into the Whites' house and starts pouring gasoline everywhere before Hank stops him from burning the house down, you can see the outline of a crew member exiting the right side of the dark living room at the beginning of the shot. (00:21:35)
Continuity mistake: In the car when Walt meets up with Saul and discusses "Old Yeller" Walt asks what he means and is looking at Saul. When it cuts to a close up of Walt, he's suddenly looking more straight ahead or towards the driver, only then to turn his face to Saul.
Chosen answer: It is part of the ritual for la Santa Muerte. It is a sign of humility and sacrifice.
djm