In one of the news broadcasts Megan is described as twelve years old, weighing fifty two pounds and measuring three feet and five inches tall. She is clearly much taller than this and almost certainly weighs more. Those measurements would be about right for an average six or seven year old girl.
As the two Secret Service men are running past the front gate after the kidnapping, the bar on the gate has been lowered and they run around it. In the video tapes of the same scene that Cross reviews, the two men run straight out into the street, and there is no bar blocking their path.
When Alex Cross breaks into Jezzie Flanagans apartment, he is shown turning on her computer. But the monitor is already on and showing a blue screen before he reaches the desk where the computer is located.
When Alex enters Jezzie's apartment towards the end of the film, he lowers his gun slightly so it is aimed at the floor. The shadow of him holding the on the wall in the right corner shows the gun held up and aimed in a completely different direction.
The teacher talks about Lindburgh. He turns to the blackboard and writes at or just above his eye level. Yet when the camera views his face from the blackboard, he is writing at or below his shoulder height.
At one point, we see Alex drive past a Save-On-Foods supermarket. (You can tell by its trademark neon lights.) However, Save-On-Foods only have stores in the Canadian provinces of British Columbia and Alberta.
The kidnapper tells Cross to run from the Watergate to 6th and Pennsylvania Avenue in 14 minutes, a distance of 2.1 miles. Then the kidnapper instructs him to double-back to 12th and Madison in 12 minutes (another .6 miles). The pay phone at 12th and Madison does not exist, that address is in the middle of the National Mall. The kidnapper then instructs Cross to get to Union Station in 4 minutes which is another 1.5 miles. First, that last leg of the run is ridiculous. Secondly, that is a total of 4.2 miles of running 30 minutes-not a bad workout in a full suit, trench coat, and dress shoes.
Cross and Jezzie get on the Washington, DC Metro at Union Station, but when the train is shown coming out of the tunnel it is a different train type than that used on the metro and has a red-and-blue "MTA" logo on the front instead of the Metro's brown "M" logo - it is in actuality the Baltimore subway.
Going to the school, Cross heads west into Virginia from the Lincoln Memorial. Coming back, he also heads west along Pennsylvania Avenue (with the Capitol dome in the background), which is east of the Lincoln Memorial.
While going through the files on the computer at Megan's desk, Agent Hickley describes GIFs to Dr. Cross as being made up of billions of ones and zeros. In fact, even just one billion binary bits (ones and zeros) would be over 100 megabytes - at least a hundred times the size of typical GIF images.
When Cross enters Union Station, the caller tells him to get on "the Metro", which is the common term for the Washington DC subway system. A few scenes later, a news reporter refers incorrectly to the subway system as "the MTA".
When Alex accesses Jezzie's computer he is prompted for a password. When he enters the password we see the actual characters he is typing where in actual fact, most Windows-based programmes would only display a line of asterisks.
The kidnapper tells Cross to board the Washington Metro at Union Station and specifies a platform number. The Amtrak out of Union Station uses platform numbers, while the Washington Metro uses street names and not platform numbers on its stops. Also, Jezzie and Cross are seen moving between cars through the doors at the end of each car while the train is moving, something permitted on Amtrak but not permitted to riders under any circumstances on the Washington Metro.
When Jezzie is trying to get Megan out of the room in the barn and she shoots through the door of the room, she shoots at least 20 times with a pistol that should hold no more than 15 rounds even with a staggered magazine.