The title card "Hitting a bullet with a bullet" is shown over a reenactor from Gettysburg. Famously, there is an example of a bullet hitting a bullet and fusing together at the Gettysburg museum. According to legend, this happened during Pickett's Charge on July 3rd, 1863.
The narration from the trailer is of astronomer and anti-nuclear weapon activist Carl Sagan reading from the audiobook recording of his 1994 book Pale Blue Dot.
The Presidential Emergency Briefcase containing the nuclear weapons launch codes, which is being guarded by a military aide to the POTUS, is known as the Nuclear Football. The POTUS also has a special code printed on a plastic card called biscuit, which he must use to authenticate himself to the deputy director of operations at the National Military Command Center.
The movie features the 162nd re-enactment of the Battle of Gettysburg, placing the events in movie in the year 2025.
Exterior shots for the Alaska sequence were actually filmed in Iceland with limited time that added to the film's urgency. In a Tudum article, Anthony Ramos says "Just arriving and then them being like, 'We're running out of light. Please hurry up and get in your costume and let's shoot this,' kind of just gave me this sense".