Computer-generated imagery
A bridge scene was filmed for six consecutive nights in January on the Brooklyn Bridge to serve as a flashback scene in which New York's citizens evacuate the city. Shooting the scene consumed $5 million of the film's reported $150 million budget, which was likely the most expensive shoot in the city to date. The scene, which had to meet requirements from 14 government agencies, involved 250 crew members and 1,000 extras, including 160 National Guard members. Also present were several Humvees, three Strykers, a cutter, a utility boat, and two response boat small craft, as well as other vehicles including taxis, police cars, fire trucks, and ambulances. Filming concluded on March 31, 2007. Computer-generated imagery (CGI) was used to depict the main spans of the Brooklyn Bridge and the Manhattan Bridge collapsing as missiles from passing military jets blew them up to quarantine Manhattan island.