The comet is named "Clarke," in a tribute to the late Arthur C. Clarke, author of the 1993 novel "Hammer of God," which describes the impact on Earth of a planet-killing asteroid. The novel predates the movies Armageddon (1998) and Deep Impact (1998), which deal with similar events.
The QR code John receives from the Department of Homeland Security is a functional one. If scanned, it displays the text "GARRITY, JOHN A."
Produced with the full co-operation of the US Department of Defense.
It is estimated that the film made around $32 million through video on demand.
On the wall of Dale's (Scott Glenn) workshop is a plaque indicating he was a veteran of the 173rd Airborne Brigade, "The Sky Soldiers".