Trivia: Don Cheadle improvised a large portion of his dialogue in the movie. He also embellished many scenes with improvisation like when he pushes the door on the lawyer in the beginning of the movie.
Trivia: The scene with the helicopter putting the bus on the building was technically impossible as no building roof could hold that weight safely. So the crew built a set of the roof that was reinforced to hold the bus. The rest of the city was CGI inserted around it.
Trivia: Very little of the bus/helicopter scene was CGI. The director insisted that a real helicopter be used that could handle the load. This made the crew and the pilot extremely nervous as the load was almost 80% of the helicopter's capacity. The stunt crew held firm on the scene where the bus crashes into a meeting however. That was completely CGI as the pilot insisted that it was way too dangerous to attempt it even with a fake building.
Trivia: John Travolta turned down the role of Gabriel a total of six times. He eventually changed his mind when he heard director Dominic Sena's take on it.