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: In the final fight scene with Harrison Ford, the bad guy's hair grows longer then shorter then longer from shot to shot.
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!
Other mistake: The steamship shown in Patriot games is actually a shot from John Wayne's 1955 Sea Chase.
Visible crew/equipment: At 11:55 into the film you can see a camera on a dolly along with the focus puller in the left side of the shot (wide screen version) for roughly 6 seconds.
Continuity mistake: When Sean Miller is being transported from the court, we see identical prison vans surrounded by Vauxhall Cavaliers. When the terrorists spring Sean from the prison van, the burnt out wrecks in front and behind the prison van are actually Ford Sierras.
Continuity mistake: When Jack Ryan gets in his car outside the Naval Academy to chase after the terrorists, he locks the driver's door as an officer comes up to the window to ask if he's okay. Moments later as Ryan is driving, the door is unlocked again.
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.
Continuity mistake: When Cathy Ryan enters the highway off Rowe Blvd (before the crash), she's supposedly heading toward DC. In fact, she continues back toward Annapolis instead of toward DC.