Several of the characters board the elevator at the 40th floor. The elevator is shown dropping to the 39th floor before it goes haywire, the characters panic, and the elevator is shown careening downwards in the elevator shaft. Yet when the floor numbers are shown inside the elevator again, the numbers are in the high 30s, indicating that the elevator has not dropped much at all.
When Caleb breaks through the drywall into the next apartment, the hole he makes is about 2 feet wide or more. This would be highly unlikely since drywall is almost always installed over studs that are spaced 16 inches (or less) apart.
Some building codes allow studs to be on 24" inch centers for non-load-bearing walls.