During the opening scene, one minute before impact, the TV hostess talks about live images from the Hubble Space Telescope.
The HST is designed to observe deep space, it is not able to make images on close objects such as a near-to-impact comet.
General officers in the United States Army wear rank insignia on the center of the shoulder boards and not the ends.
The US plan is revealed as "Operation Saviour" which is the obvious British spelling, as opposed to "Operation Savior" which would have been the US spelling.