Doesn't necessarily need to be if what these reviewers are saying is true:
"Mandalay Bay was Disappointing
Posted Aug 17, 2015 on Hotels
The floor to ceiling windows whistled loudly whenever the wind was blowing in the right direction. Adjusting the vent on the window did not help."
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5/11/2010 - The vent on our window was broken so majority of our stay our room was noisy from the wind and outside noise."
https://www.yelp.com/biz/mandalay-bay-resort-and-casino-las-vegas?hrid=XMTQEHB5rr5SsJPpOxCi4A
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"Mandalay Bay also has those little "ventilation strips" that you can slide open".
Mar 06, 2008
https://www.tripadvisor.com/ShowTopic-g45963-i10-k1793764-o10-Windows_opening_do_any_strip_hotels_have_windows_that_open-Las_Vegas_Nevada.html
It appears there may be some guest rooms at Mandalay Bay (lower level??) that have some kind of window vent. If true, could be used as a gun port, basically, without having to bust out the window. Not saying there was a 2nd shooter, just and observation.
That would make it harder to shoot. We don’t know what size they are talking about, either. Whistling winds would indicate they are small.
Gun smoke would make another location easily identified.
Neighboring rooms would be aware of gun fire. Must have sounded like a jackhammer in the room.