The first time the whole exterior of the Zurich Hotel can be seen, just before the 10-minute mark, the large red Z on the side of the hotel appears to be above the 18th floor. The next time the full exterior of the building is shown, just after the 19-minute mark, the large red Z is just above the 10th floor and the entire hotel appears to be less than 18 stories tall.
Desi identifies Paula's gun as ceramic. A few minutes later, Riley tells Paula that she'll have to leave the gun behind because the Grand's metal detectors might pick it up. Metal detectors won't pick up a ceramic gun: that's how Paula smuggled it into the Grand.