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At around 35 minutes when they are initially looking back to Claire's house, as the camera is identifying and zooming in on, and through, her front door, you can clearly hear a set of tones that are identical to the tones that come from the computer display in Gaff's spinner in Blade Runner (1982) toward the beginning of that film. Ridley Scott, who directed 'Blade Runner', is the older brother of the late Tony Scott.
The movie went through pre-production in New Orleans. Just a few weeks before production was to begin, Hurricane Katrina devastated the city. With the location in ruins, the movie made the decision to find a new location to shoot. A few weeks after the decision, canceling the movie altogether was in talks. Finally, three months after the hurricane, the film returned to New Orleans, Louisiana and began pre-production once again.
While working on the film, first assistant cameraman Michael S. Endler learned that his father, Gerald Endler, had died. As a tribute to Gerald, a former special effects technician who had actually worked with many of this film's effects crew decades earlier on other projects, Michael was allowed, on the day of shooting the ferry explosion, to place some of his ashes on a gasoline-filled water jug that would be blown up as part of the pyrotechnics of the sequence (which was referred to on call sheets as the "Stumpf Ferry Gerald Endler Memorial Pyro Blast").
Tony Scott, Denzel Washington, Val Kilmer, and Jim Caviezel held a news conference upon their arrival to New Orleans to announce their intention to employ the local New Orleans community and incorporate post-Katrina New Orleans into the film.
Tony Scott and Val Kilmer had shirts made for the crew that said "Malcolm X, Jesus Christ, and Jim Morrison: Deja Vu. How Can We Fail?" Denzel Washington played Malcolm X in Malcolm X (1992), Jim Caviezel played Jesus Christ in The Passion of the Christ (2004), and Kilmer played Jim Morrison in The Doors (1991).
Disaster relief teams, who helped through the aftermath of Hurricane Katrina, were recruited to help make the film. The end credits pay tribute to their bravery.