Continuity mistake: When Emilio's body crashes through the ceiling and lands on the downstairs floor, there is one huge chunk of carcass that lands on the floor in one piece. When the remnants of the body are shown from a different angle, they have been replaced with numerous, smaller chunks. (00:45:30)
Continuity mistake: At the end when the girl puts the mask on there is a bit of hair hanging over the front of the mask. Camera changes and the hair has disappeared. (00:46:10)
Chosen answer: It is part of the ritual for la Santa Muerte. It is a sign of humility and sacrifice.
djm