Other mistake: Walt takes new-born Holly into the garage to show her the money hidden behind wall insulation. He enters through a door that doesn't exist in the interior of the house. (00:15:00)
Continuity mistake: When Jane OD's and starts to vomit, puke falls by the left side of her mouth. In the following angle the mouth is clean. (00:43:50)
Continuity mistake: When Hank arrives with takeout food from Los Pollos Hermanos, Walt picks up a container, but in the next shot he isn't holding it. Also when Walt places a chicken breast on Skyler's plate, it disappears in the next shot, but re-appears in the shot after that. There is a lot of back and forth with the food in this scene. (00:11:45)
Continuity mistake: Walt's grip on the needle changes position at the end. In one shot he is holding it very close to the needle end, in the next he is holding it by the plunger end. (00:43:20)
Visible crew/equipment: When Skyler asks Walt if he is learning about elephants, Walt looks up to Skyler and in doing so a light screen is reflected in his glasses. (00:34:00)
Chosen answer: It is part of the ritual for la Santa Muerte. It is a sign of humility and sacrifice.
djm