Corrected entry: When Leo Beiderman and his family are watching the live report from the White House, in which the President tells the world about the asteroid discovery, he also mentions that the asteroid will be named Leo Beiderman. After a moment the phone rings because someone heard about Leo on TV and when the door bell rings Leo opens it and he sees all his neighbours. It's absolutely impossible for them to get to his house that fast. They only just heard his name on the TV and after a few seconds all of them are already at his door.
Corrected entry: The young protaganists are supposed to be in a public high school in Richmond, Virginia. However, the student body appears to be 95% white and there are no apparent southern accents. In reality, most high school students in Richmond have very obvious southern drawls and a solid majority of students are African-American.
Corrected entry: In the scenes that lead up to the impact of the meteor, we're shown horrible traffic jams with cars all over the freeway blocking everything, yet Tea Leoni can pass all that and ride out of the city all the way to the sea to be with her father and she gets there long before the impact takes place.
Corrected entry: When Sarah tells Leo there's no point in going to school, she's right - the scene is set around four weeks before the August impact, so it's July.
Corrected entry: When the President is making his speech at the press conference he says that the as comet had been seen by a Young Explorer's Astronomy Club on a mountaintop in Arizona. Then when everybody's escaping from the coastal areas and it shows Leo driving down the highway looking for his girlfriend there's a sign for Virginia Beaches. Arizona is a pretty long way to go on a field trip, don't you think?
Corrected entry: Leo reports his discovery to the local professional astronomer, who programs his software to plot a course for The Comet. It displays a three-dimensional graphic which shows the comet headed right for Earth. In his panic to report the discovery, he wrecks his car. First off, Leo should have reported the discovery to the International Astronomical Union's Minor Planet Center (http://cfa-www.harvard.edu/cfa/ps/mpc.html). We can forgive him this breach of professional etiquette since Leo wanted to report to his club's sponsor first. The real problem is that it takes several observations over many nights to get a good orbital calculation for comets, especially one that's a year away from impact. It's like looking at a snapshot of a baseball and being asked when it will hit the ground. What direction is it heading? How fast is it moving? One observation doesn't really tell you anything; you need to see it move. The 3D graphic was a bit over the top too. While not really impossible, it's more of a Hollywood silliness. It's there simply to drive the point home that we're in for a bit of trouble.
Corrected entry: In the opening scene, we see a group of young amateur astronomers stargazing. As we pan across the group, we see them studying maps with flashlights. The problem here is small: using a flashlight outside at night ruins your dark vision. The eye takes quite a bit of time to get adapted to the darkness; usually twenty minutes to get fully adjusted (less if you are in a light polluted area). Using a white flashlight destroys the very reason you're outside! However, the eye's dark adaption is not ruined by red light, so astronomers use red flashlights (usually modified by the high tech method of taping red cellophane over the business end of the flashlight). This may have been plot-driven; we'd want to be able to see the actor's faces.