When the student is talking to Ethan after he is picking up Zooey at school, the student makes a cowboy reference. Kevin Costner played western lawman Wyatt Earp in Wyatt Earp (1994). [Alternatively, the "cowboy" reference could also be to Costner's even earlier breakout role in 1985 in the great movie, "Silverado."]
Ethan is seen rescuing Zooey from a group of boys in the washroom then proceeds to carry her out of the nightclub. In The Bodyguard, Kevin Costner's character rescues Whitney Houston from her fans on the stage and also ends up carrying her out of the nightclub.
Elevators do not just drop when a cable connection is either lost or otherwise interrupted by shooting; the safety system invented by Elisha Graves Otis in 1852 locks the car in place and prevents it from falling.
What are the differences between the Theatrical Version and the Unrated Version.
Even though Besson's work are usually shot based on the viewing habits of an European audience and then being censored for the more lucrative "PG-13" rating, 3 Days to Kill has written "PG-13" all over it from the very beginning. Sure, there has been released obligatory Unrated Version but additional violence can barely be found. The most significant censored scene is the one at the strip club. Other than that, the differences usually affect the story or dialogs. To get an impression of the movie, the Theatrical Version will do the trick because the 5 minutes of new footage could be called anything but elementary. Nonetheless, one would rather watch the most complete version of a movie. A detailed comparison between both versions with pictures can be found here.