Many actors who appear in this episode have previously appeared on episodes of 'ER' with Laura Innes, including Clifton Collins Jr., Zeljko Ivanek, Clea DuVall, Michael Whaley, and Scott Michael Campbell. Evan Katz, executive producer of "The Event," has similarly worked with many actors in this episode on episodes of "24" including Campbell, Ian Anthony Dale, Bill Smitrovich, D.B. Sweeney and Omid Abtahi. Series regular Lisa Vidal, who does not appear in this episode, has also worked with Innes on "ER" and Zeljko Ivanek played a main villain on "24" during the first season, long before Katz was a show runner.
The computer seen in the opening credits is made up from components of an IBM AN/FSQ-7 Combat Direction Central, built in 1954 to protect the US from Soviet bomber attack. It was the largest and heaviest computer system ever built, the full system weighing 6000 tons and taking up an entire floor of a bomb-proof blockhouse. Components of decommissioned systems were sold for scrap and bought by film and television production companies who wanted futuristic looking computers, despite the fact they were built in the 1950s. The components used in this episode were previously used in 'The Time Tunnel (1966)', 'The Towering Inferno (1974)', 'Independence Day (1996)', 'Fail Safe (2000) (TV)' and 'Austin Powers in Goldmember (2002) ' amongst many others.