Continuity mistake: As Gant is pulling the Firefox out of the hangar, it is still very dark, as in pre-dawn. But as the Russian officers are shown shooting and watching the Firefox take off, it is suddenly much lighter outside as if it is after dawn and the sun can even be seen. But it would have taken 30-60 minutes for the light level to change that much.
Factual error: When flying towards the Russian missile cruiser, Gant says that "infra-red detection beams" have locked onto the Firefox. There is no such thing - infra-red (heat) sensors are entirely passive, meaning they do not give out any kind of signals and cannot be detected.
Continuity mistake: Immediately after Gant steals the Firefox, the main screen in the middle of the cockpit states that he only has three missiles in the third missile bay, while the others are full. Later on, when he fires on the recon plane, all missile bays are now listed as full.
Deliberate mistake: When the security forces arrive at the hangar to report seeing Gant at security gate 3, they are driving an American Jeep.