Toward the end, after Ricky decapitates the old Mother Superior, a young nun assumes she is alive and taps her shoulder. Mother Superior's head falls off and to the floor. There is no blood whatsoever. The old woman had just been decapitated moments earlier, and there isn't even a drop of blood, not even on the white part of her nun outfit at the neck.
The house number of the strict, God-fearing mother superior is "666" - the number of the beast.