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. And the novel "Lucifer's Hammer" written by Larry Niven and Jerry Pournelle, was written in 1977, and predates Clarke's novel.
The location footage of Greenland at the end of the film is actually of Iceland. For example, the picturesque waterfall at 01:38:14 is Skógafoss on Iceland's southern coast.
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.