When the body is first seen on the autopsy table, his eyes are open. However, when Sid turns the body's head 90 degrees to the left to investigate what caused the blunt force trauma, the body's eyes are closed.
Without an oxygen tank or some other form of ventilation, Anthony wouldn't survive a few hours sealed in the casket, never mind 48 hours.
When Mac checks for liver temp on the kid in the grave, he sticks the instrument on the wrong side of the body.