Continuity: In the scene where Ethan is in the NOC list room Krieger starts to drop him and Ethan is hanging there for a little while. Suddenly some sweat starts to drip down his glasses and he catches the drop with his hand. If you look at how close he is to the floor this move would be impossible.

Factual error: The train is a French  TGV, these do not operate in the UK (not to date anyway) The Channel Tunnel passenger train is the Eurostar.

Factual error: Max@Job 3:14 is an illegal e-mail address.

Continuity: Besides the fact that during the final action sequence it is impossible for two trains to occupy the same tunnel, how is it that the blades of the helicopter attached to the first train don't strike the second? Tight fit.

Continuity: When Tom goes to the restaurant to meet with Henry Czerny, the plants in the aquarium are noticeably different after he goes inside.

Continuity: When Ethan is being lowered into the room with the NOC List, he has the digital temperature gauge. As Ethan is going down, the gage is right side up so you can read it normally. However, Ethan is upside down, and therefore so are the camera glasses he is wearing. Now when we see the computer screen that Ving Rhames is using, the gauge is right side up there, but it should actually be upside down.

Factual error: In the scene where the helicopter is being flown into the tunnel, sparks can be seen on the far tunnel wall, where the rotors have hit it. No helicopter can keep flying in a straight line after the rotors have collided with a solid object in this way.

Continuity: At the end of the film, Ethan drops his mask. His hair looks flat and wet. At the next shot it's dry and up.

Continuity: The train is electric, supplied by overhead cables, which do not appear to be present at any time. If it was a Eurostar then it could use 3rd rail pick-up but it wouldn't be going so fast, but that's academic; its not a Eurostar and no 3rd rail is visible either.

Plot hole: In the air vent, we see a rat. Wouldn't rats in the vents set off the alarms on a regular basis, because the lasers were on the upper side of the vent?

Factual error: CIA headquarters in Langley has its own firefighting unit and never, ever calls for outside help.

Revealing: When Ethan uses the magnetic screwdriver to undo the screws holding the grille to the air-vent in the NOC list room, the spindle that is actually turning the screw is visible after it falls out.

Factual error: The Channel Tunnel tracks run through separate tunnels, one going to France, one going to Britain, so trains don't pass in the tunnel as they do in the film.

Continuity: During the Channel Tunnel helicopter chase sequence, the colour of the helicopter changes from red to black.

Factual error: The train is running on the right-hand track, but in the UK trains normally run on the left-hand side, same as cars on the roads.  In Europe and the US, trains run on the right-hand track.

Continuity: At the end of the movie, when Ethan and Luther are sitting at the pub, just after the cheers/here's to you speech, Luther said "Hey, I'm flavour of the month" and brings his glass up to his lips for a drink. In a split second cut to a wide shot facing Luther his glass is on the table, and there are only two glasses on the table as established in a wide shot where Ethan says, "I'd better go catch my flight."

Continuity: 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 have 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. [They don't want to leave any trace that they were there, although the accidental (or deliberate?) knife drop ruined that plan]

Plot hole: Accessing the secure room through the duct work would be virtually impossible (pardon the pun). First is this an air supply duct, return air supply duct or an exhaust duct? If it was an air supply or a return air supply duct there would be a squirrel cage fan moving the air. Not the propeller fan you see in the frame. If it was an exhaust air duct again no propeller fan. The size of whatever duct it is for that size of a room is questionable. The room was small yet the duct was large enough for a man to crawl through. The last reason why this would be impossible is where are all the screws that ducts are assembled with? They would definitely stick through the ducts and catch clothing, scratch hands, heads etc.

Visible crew/equipment: When Ethan is going down to the security room on a rope you can see a man standing on the floor at the bottom. It's right after he starts to descend.

Factual error: In the scene of the eurotunnel train the ticket collector is wearing a 70s British Rail uniform This was the national railway company for Great Britain but is now defunct due to privatisation in the 90s.