Character mistake: When the EMTs are resuscitating Dr. Harris, they use a defibrillator despite their being on a wet metal dock. Not only is this highly dangerous to absolutely everyone present, it would be completely ineffective at restarting his heart as the water and the metal would dissipate the electric current too much for it to do any good. At the very least, they would have stabilized his spine then moved him to a dry surface before beginning defibrillation. (00:08:30 - 00:09:10)
Suggested correction: External defibrillators are self grounded and so can be safely used on wet or metal surfaces. https://danboater.org/travel-health-and-safety/are-aeds-safe-to-use-in-wet-environments.html.
AEDs are indeed safe to use in wet areas - but in the film, it is not an AED that is used. AEDs are automated, and not operated by humans, so as to reduce risk. Your link explicitly states the rescuer must not have direct contact with the body: they just apply the pads, then move back. In the film, it is shown in detail that the medic applies the paddles and then operates them while still in contact with the body. The mistake stands: it's a traditional defibrillator, thus incorrectly used.
Factual error: In the last scene the ICE Train is leaving the station eastbound. It is not possible to enter these trains at the central station because all eastbound trains end in Berlin and have only one station left (Berlin Ostbahnhof). Every ICE leaving Berlin is going in the other (westbound) direction.
Plot hole: After January Jones has just told Liam Neeson she doesn't recognise him. Neeson is trying to persuade Herr Strauss and two cops that he really is Dr Martin Harris of Langmore University, and suggests they look for a photo of him online. However, the cop using the computer says that it could take him ages to find a photo of Dr Martin Harris, as "there are more than 40 000 in the USA." This is very true, but as Neeson has already told him not only his name but also his place of work (Langmore university) in reality the cop would have found the photo far more quickly.
Suggested correction: The average cop wouldn't be that quick to realise that he could filter the results. Instead of being a plot hole, this is simply a very human initial response to an initial search result.
Continuity mistake: When the nurse is giving Liam Nelson the address of the investigator, in one shot she's writing the note with her left hand, and in the next shot, she has the pen in her right hand.
Continuity mistake: In the scene when Liam Neeson wakes up from unconsciousness following his car accident, the nurse writes something on her notepad with her right hand, but in the next shot the pen has suddenly switched to her left hand as she puts it into her pocket.
Other mistake: When Martin Harris is being chased in the taxi, paint covers the entire screen. Martin asks for the wipers to be switched on, but by the time the taxi crashes, the windscreen is completely clean, with no sign of the paint. There would be wiper marks and the remaining paint on the windscreen.
Continuity mistake: The original taxi (with number) is parked outside Gina's apartment complex and they use it to escape, but it went into the river during the accident and Gina's taxi owner boss laments about it early in the movie.
Other mistake: In the first scene, Liz and Martin are driven in a taxi from the airport. The driver is on his mobile phone. The subtitles say that he is speaking German, however in fact he is speaking Turkish.
Factual error: Jurgen takes the cyanide out of a coffee tin. He mentions he has had it for years since his time in the Stasi. However, in fact potassium reacts with carbon dioxide to form a harmless compound over time: to prevent this it must be sealed in an airtight container, which a coffee tin most certainly is not.
Character mistake: The private detective tells Liam Neeson he believes his story, incredible as it is, because as a former Stasi agent, they could spot an innocent man, because an innocent man always stuck to his version of truth while a liar reformulated his ideas. However, in fact the Stasi taught exactly the opposite idea: for them, a liar has invented a pre-programmed version of the facts and cannot change it, while someone innocent can change his speech.
Factual error: Liam Neeson is holding a Rolex Deepsea marked "EH to MH 7.18.06." The watch was released in 2008.
Continuity mistake: The password needed to access Leo Bressler's hard drive, Umbellularia californica, is visible in the book. In the next shot 'umbellularia' is incorrectly typed into the password box as 'umbellurlaria', yet it gains access to the drive.
