The amount and location of the "knockout goo" on Ken's ears changes in the shots following the phone call.
When Kevin goes undercover to Hamish Intl. he takes a lot of things out of his yellow bag and then he starts putting all back. In the process, several items disappear and reappear on the counter between shots.
Leo gives Sam his gun in the basement. She aims at him. Then he says he would never give her a loaded weapon and tells her he took out the magazine. But when Sam puts the mag in and loads the gun (pulling back the slide) you can clearly see a bullet flying out of the shell ejection. So that means there was a bullet in the barrel all along and she wouldn't have needed the mag at all which tells us that Leo is not a professional or more likely that the crew screwed it up.
The counterbalance of the elevator passes the elevator at several different floors. The first time when they hang under it, the balance passes at something like the 4th floor. When Sam is going to track the guard, she is at the 22nd floor and the same happens as the elevator goes by. Both cases are not according to the indicators outside the elevator near the entrance; the 22nd floor is almost at the top of that elevator's reach. This means the counterbalance should pass the elevator at something like floor 15, not 5 and certainly not 22.
After Sam slides on the dry ice to get to the keypad, she is told to enter the number "6" but you can clearly see her reach, and press, the number "4".