4th floor plot holes ??SPOILERS??
I loved this movie but for me, the biggest plot holes were in the scene with the building/elevator at the end. So we are to believe that:
Catherine was on floor 2, knew the exact moment Gus got on the elevator on floor 1 even though she couldn't see him, hit the up button and raced up the stairs to floor 3, repeated this, got to floor 4 through the stairwell and then performed a stabbing murder in the elevator...unbeknownst to Beth - who was right there waiting to meet someone on that floor?!
Aside from the first part of that being tough to accept as possible, I can't believe that anyone, let alone someone as smart as Beth, wouldn't have the slightest clue there were neither stairwell and elevator character entrances nor someone being stabbed brutally and repeatedly. Especially when you're told to meet someone on a random floor of a hotel at midnight, you're going to be alert and look out for your safety and notice things like this.
Not to mention that she's a professional communicator...yet couldn't communicate to her boyfriend that she was unarmed?
It was too much for me to believe.