The Day the World Went Away - S5-E10
Continuity mistake: As Finch and Root are being chased by an SUV equipped with a mini-gun, Root uses a.338 Lapua to shoot the SUV engine four or five times. As Root descends back into the car the rifle in question is plainly a bolt action precision rifle. (00:28:55)
Factual error: Samaritan launches a cruise missile at the rooftop of 1133 Avenue of the Americas, where a satellite dish is located. A real US Navy Raytheon SM-6 missile, fired from a surface ship, would shoot down the cruise missile shortly after it was launched and long before it hit NYC.