It's funny that you mention that, since Universal used to implement HHN into certain attractions in the park. While the execution was never anything to get excited about, I always like how they tried, and wished that they had gone to the next level.
As far as the Mummy queue goes, I've seen the TM's hide and scare guests on several occasions. I don't supposed it would be much of a stretch to whip up some mummy costumes and throw them in the queue. I'm all for it.
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