Best crime movie factual errors of 2012
Factual error: When the bridges are blown up, some of the bridges are suspension bridges, but the bridge only fails at the point of the explosion. The main horizontal supports are severed, but large portions of the bridge remain magically aloft. The nature of suspension bridges means the remaining vertical cables and road deck would fail as well, resulting in the loss of the bridge between the two main pillar supports.
Factual error: Liam Neeson asks his daughter to set the grenade off and counts to 4 after that. He then calculates the approximate distance of the hotel from the place he was taken to, by multiplying the speed of sound (0.34 km/s) by the time taken for the sound to reach him (~4 seconds). Given those numbers, the distance between him and his daughter is about 1.36 km, whereas he calculates it to be 4.5 km. He also makes a minor slip up in using "circumference" instead of "diameter" when she draws the larger circle, but that's incidental to the real mistake here.
Factual error: When Ranger takes Stephanie to buy a gun, the one she gets is a 5-shooter, but in the scene where she is firing it at the gun range by herself she shoots it 12 times without reloading. Later, in the scene where she shoots Jimmy Alpha, she fires it 7 times without reloading.
Factual error: When Bradley Cooper is leaving the Police Station in the 1990's, he is being watched by Ray Liotta by the street. You can see a silver 2010 Hyundai Sonata drive right past them, a model that doesn't get built for another decade. There's also a GMC cargo van parked across the street that looks like it was built after 2009.