After retrieving the NOC list from Langley, and escaping to London, Krieger pulls the disc from his pocket and attempts to blackmail Ethan. Ethan responds by making another disc vanish in a feat of magic. Krieger, angry, storms from the room and chucks the disc he had into the wastepaper basket. It clearly breaks into several pieces. You can even see a chunk fly up out of the basket, yet when Ethan pulls it once again from the basket, it's perfectly intact.
When Tom Cruise is talking to Krieger and the other guy on the train about breaking into Langley, he clearly states that any noise above a whisper would trigger the alarm system, but the noise he makes when he's getting pulled up from the room is much louder than a whisper.
Max@Job 3:14 is an illegal e-mail address.
Claire leaves the firefighter uniform in the closet but is seen wearing it again in the truck while leaving.
During the scene where Ethan is hanging in the bank, he can't talk or he'll set off the sound-sensor; he can't touch the ground because of the weight sensor; and he can't cause the room to get too hot because he'll set off the heat sensor. If there were a vent, the temperature would most likely change. Why isn't there a motion detector?
In the secure room, why didn't they just knock the guy out and tie him up? Then they wouldn't have had to worry about alarms at all! Claire wouldn't of even had to go inside and they wouldn't have needed all that computer technology. Ethan was hanging right over top of him and easily could have handled it.
When Tom Cruise walks along the bridge just before he jumps into the water to escape - it took them 25 takes and 2 hours to get that right.
The first time he mails to Job 3:14, later he mails twice to Job 3:15.
A lot of technical stuff surrounding this, but basically any depiction of the train at the end is wrong, what with tracks, overhead wires, luggage carriages....you name it, it's wrong.