When John and Karl are fighting and Karl reaches for the gun lying on the floor, John legs it out of an open door. Karl fires two shots the first hits John and the second sprays blood all over the door. Hans can hear what McClane is saying. You cannot hear anyone on a walkie talkie while your transmit key is pressed. When the police officer comes in to check if everything is fine, on the T.V. there is a football game.
Football has quarters.
After killing the first terrorist, John tries on his shoes and finds that they are two small. There is a scene where Bruce Willis and Alan Rickman meet. Rickman poses as an American employee of Nakatomi who escaped the terrorist siege of the building. Beretta 9mm handgun implying that Rickman might help Willis fight the terrorists. Rickman then turns it on Willis.