Continuity mistake: When the terrorists attack the van at the bridge, shortly after the explosion, you see the terrorists crossing the water in a boat. In the background you can see the van on the bridge with its doors open, shortly after this the terrorists are at the van doors demanding that the police open the van doors!
Factual error: Just before Sean Miller shoots the bookseller he takes the safety catch off the Ak-47. However, he moves the catch two clicks down and then fires the weapon on automatic. This is incorrect. For most modern weapons the safety catch feature goes safe-semi-auto, however the AK safety catch goes safe-auto-semi.
Continuity mistake: When the bookshop keeper runs from his store in Piccadilly he enters Aldwych tube station this is impossible as said tube station is a 20 minute bus ride away. Also when he gets on the train the conductor announces that the train will stop at Leicester Square, Piccadilly circus (were he just left from), and Oxford Circus This is impossible, as no train on the London underground makes stops at all those stations. He would have to change trains at Piccadilly circus.
Continuity mistake: When Jack rushes to save his wife and daughter from the terrorists on the freeway, there is a shot where he turns onto another road. Throughout this scene his seat belt goes from being buckled, to unbuckled quite a few times.
Visible crew/equipment: Early in the the film, after the attack in a shot with police tape in view, you can see a camera on a dolly along with the focus puller in the left side of the shot (wide screen version). (00:11:55)
Factual error: There is no way a highly dangerous prisoner like this would be in a convoy waiting for a bridge to be raised all routes would be cleared for the convoy to pass and there would be armed response at several checkpoints along the route whatever was passing that bridge would be told to wait and like it. (01:00:28)
Continuity mistake: When Annette goes upstairs to the bedroom, we see a brief shot of her Uzi. There is no magazine inserted. Even the 10 round magazines stick out about half an inch and would be visible. When Jack picks up the Uzi after Annette is knocked out, suddenly, there's a magazine in it. (01:39:35 - 01:40:03)
Revealing mistake: When Sean shoots at Dennis the Bookseller's feet, puffs of sand do not erupt from the ground.
Factual error: Lymington does not contain a rising bridge, only a small ferry to the Isle of Wight. It is only a small town, and not the built up area as presented in the film (the scene was filmed at Canary Wharf in London). Interestingly, the original novel is much more accurate with Clancy explaining in precise detail the route including highway numbers and towns the van travels through to reach Lymington, and the crossing is correctly undertaken on a ferry, not a rising bridge as depicted in the film.
Character mistake: When Greer and Cantor visit Ryan's home after Miller's escape, they state that he was being moved to HMP Albany on the Isle of Wight (correct, given it was a Cat A dispersal prison at the time and regularly used for IRA prisoners) however Greer later states "it happened in Kent, near the channel", which is incorrect. Lymington (as stated by the guards over the radio in the escape scene) is in southern Hampshire - over 90 miles away from Kent and on the other side of the country.