When Dr. Mayfield is driven back (the first time) by MP, the car shown is a Nissan Pathfinder. When the polar storm comes a Ford Explorer is shown, which is also the car with which he is picked up and returned at home.
After a "major" earthquake at The Park area, Shane and Zoe are shown walking down the road to get home. We never see any news or emergency services people looking to see if there were any injuries, or what the damage really was.
When the comet fragment is falling to Earth, Pam tells James that is going to land at 51 latitude, 179 longitude, and warns him that that is only 100 miles from his location. However, James and his partner were at the Arctic Circle in mainland Alaska; 51N 179W is about 17 miles south of Amatignak Island in the Aleutians, about 1500 miles away.
The opening scenes are full of technobabble and gobbledygook. For example, when the comet appears, a character says the radiation level has risen to 4.5 Angstroms; however, an Angstrom is a unit of distance, one ten billionth of a meter, used to describe wavelength of radiation not level of intensity. Another character mentions that the comet has reached "orbital fulcrum"; that is a meaningless term used solely to give the ignorant viewer the impression that the speaker is a rocket scientist.
There is no way that a diesel powered submarine could make it from the West Coast to the Marianas Trench on the other side of the Pacific Ocean as fast as it did in the film. There is also no way that a diesel submarine could go down to within 100 ft of the bottom of the ocean where the depth is 10,911 meters or 35,798 feet. The only vessel to have reached that depth is the specially built vessel the Trieste. (The Trieste had one of it's Plexiglas windows shatter at 9000 m., the two men inside thought they would be dead within minutes. Only two other vessels have made it to the bottom of the Challenger Deep since the Trieste's voyage. Both were unmanned, A Japanese robotic craft Kaiko reached the bottom of the Challenger Deep in 1995. The Nereus hybrid remotely operated vehicle (HROV) reached the bottom on May 31 2009.)
The telescope shown early in this move is an inexpensive 4 1/2 inch (or possibly 6 inch in diameter) Newtonian type telescope. Since the model shown is clearly mounted on an inexpensive German Equatorial mount, it certainly has a value of no more than $400.00; not the $4000.00 as suggested.
After Mayfield attaches the timer to the bomb he puts a thin metal cover over the opening. There is nothing to prevent sea water from entering and damaging the bomb. Also, pressure at the bottom of the Marianas Trench is approximately 15,750 psi (over 7 tons psi). The bombs would have been crushed as soon as they were placed in the water.
The diesel submarine shown is a World War II design which even includes an anti-aircraft gun platform aft of the conning tower. Modern diesel submarines (even old ones used for training) have a hull form similar to those of nuclear submarines.
When Mayfield is attaching the timer to one of the bombs he uses alligator clips to make the connections, then stuffs them into the metal housing without insulation. This would result in them shorting out and not triggering the bomb.
Zoe's father has a pacemaker, which is shorted out when their car is hit by one of the EM pulses. After the car is hijacked and a second wave hits, the pacemaker is seemingly shorted out again, resulting in his death. However, as the device had already shorted out, nothing would have happened as a result of it being hit by a second EMP.
When the telescope is knocked over, it falls apart too easily and in a manner unlikely if it were a real scope. The glass shown is too thin and is clearly not the relatively thick glass mirror found inside such a telescope.
Dr Mayfield, his father and two soldiers load an atomic bomb into a truck with very little effort. A nuclear warhead should weight at least a few hundred kilograms in order to get the power needed in the movie.
The goof item below may give away important plot points.
The suggestion that a change in the axis of the Earth would only be noticed by a single scientist and that the information could be classified by the U.S. government to keep it secret, is absurd. There are thousands of scientists and hundreds of institutions which would be able to make such a determination in detail, and are not under the control of the U.S government.