Continuity mistake: The Salamancas brothers burn Arturo's body inside his car. When the brothers leave, there is a scenic tree a short distance down the road from the burning car. It balances the shot. When the camera angle changes to a wide view, there are no trees anywhere near the car.
Continuity mistake: The sky changes multiple times during the opening sequence. It goes from clear and sunny to much cloudier depending on the angle.
Continuity mistake: Near the beginning when they are staging the crime scene, the car with the flat tires moves between being on the road and further off to the side during the angle changes.
Answer: The bulldozer could be disassembled, the individual pieces carried down, and then reassembled once underground.
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