Other mistake: Gus is talking to his employee about the twins while writing something on a clipboard. However, he is using the opposite end of the pen and just pretending to write. (00:14:40)
Visible crew/equipment: During the shot from the interior of the car of Hank following Jesse, a camera man in a green T-shirt can be seen crouching down on the road to the right of the screen. (00:30:40)
Continuity mistake: Walt asks Gale to recite the poem he mentions, which Gale does, reluctantly. When he starts the first line, the camera is behind him and he lifts his head to look up at Walt straight in the eyes. When the camera cuts back to a shot of his face, he's suddenly looking down again.
Continuity mistake: When Walt asks for the RV to be destroyed, there is tape over the bullet holes on both the inside and the outside of the door. However, when Hank is showing the bullet holes to the owner of the lot, he takes the tape off the outside and the light shines on Walt. No-one has touched the tape on the inside. (00:28:50 - 00:36:00)
Chosen answer: It is part of the ritual for la Santa Muerte. It is a sign of humility and sacrifice.
djm