Continuity mistake: When Jackie and Watson are driving Watson's car right after they've been on a video conference with all the professors, they park the car. We see Jackie has his seatbelt on, but when it cuts to him breaking the door off the seatbelt is no longer on him. He could not have removed it that fast.
Continuity mistake: In the beginning when Snakehead has received the book from the old man he says "The only pitiful is your life". He grabs a knife and we see him stretching his arm out against the old man. When it cuts Snakehead has his arm bent with the knife under the old mans chin. The way Snakehead stretched his arm he would have stabbed the old man right in the face, not placing the knife under his chin.
Other mistake: When Jackie meets the boss of the Interpol department in Ireland, he shows everyone some sketches, the child and then a man with a hat. If you watch the picture, it changes from a man with a hat to another man without a hat back to the man with the hat and once again back to the man without the hat.
Factual error: Throughout the film all cars have errors in license plates, In Ireland since 1992 all cars start off with last two digits of the car's year, county registered in and order registered in. Example: The first car registered in Dublin this year would be "05 D 1" the 922nd registered in Cork would be "05 C 922" I can't remember the exact format of the plates but remember it's factually incorrect.
Deliberate mistake: When Jackie tries to avoid the Jamaican guy he jumps up to a higher deck. As we see him duck out of sight it takes him about 1 second to get to the other side and jump down there. However it's at least 40 feet to get to the other side. Jackie is usually fast but not that fast.