Audio problem: The message from Walt that Skyler listens to at the office is different from the audio earlier in the episode. Walt says "no" when we see him, but on the recording he doesn't say it.
Continuity mistake: In her office, Skyler brings up to her boss, Ted, an issue with a "Keller Account" and puts one hand up to her mouth. In this shot her other arm is crossed over with her other hand resting on the one arm held up. When the angle changes suddenly her arm is outstretched more in front of her with her hand on her papers.
Continuity mistake: Walt Jr. throws up the alcohol into the pool and some of it gets on the side walls. In the wide shot this has all disappeared.
Visible crew/equipment: In the scene at the very end, Walter breaks into Jesse's house to take all of their product. As he leaves the kitchen, just as he passes the fridge, Jesse (passed out in this scene) or a crew member can be seen peeking around a doorframe. (00:46:25)
Visible crew/equipment: When Combo is watching a black car parked in front of him while he was dealing as the episode started (a few moments before he's killed), a stage light can be seen reflected in his sunglasses.
Continuity mistake: The candles on the cake at the party change height a few times during the sequence.
Continuity mistake: After Combo is killed and Skinny leaves the operation, Jesse and Walt are in Saul's office, explain what happened, and they start bickering. From a side angle you see Saul lean forward in his chair as he yells "Guys guys!" to try and stop them. It then cuts to an angle showing Saul from the front and he's suddenly leaning back in his chair, not forward.
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)
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)
Chosen answer: It is part of the ritual for la Santa Muerte. It is a sign of humility and sacrifice.
djm