Factual error: When Tom has decided his scout group will have to go for the food and then his look for his son later, they are stood on a green. There is a war memorial dedicated to both World Wars, 1914 - 1918 and 1939 - 1945. That's got to be in Canada, as the USA didn't enter either war until later than those dates. (00:28:00)
Character mistake: Tom Mason makes references to smaller armies defeating larger ones, of which history is rife with examples. He cites the Scottish defeating 'the British' at the Battle of Stirling Bridge. 'The British' did not exist at that time. The Scots administered a beating against the English in the Scottish War of Independence, against the Earl of Surrey, under Edward I. Someone with his level of knowledge would know that.
Revealing mistake: In the first scene, young people are removing scrap from a rooftop. The camera angle changes to look over the rescue team and back at the roof. In the distance, visible in the upper left of the screen, a Canadian flag is waving in the breeze. Also a short while later the camera looks back over the team away from the children, and the CN Tower appears to be in the background. Like many TV shows, Falling Skies was filmed in Canada, but the events are supposed to take place in Massachusetts, USA. (00:00:25 - 00:02:00)
Continuity mistake: When Tom starts shooting at the skitter in the food depot, the shots from his gun, the hits on the metal, and sound of ricochet are inconsistent with each other.
Continuity mistake: The muzzle brake on Noah Wyle's rifle keeps changing from the flat muzzle to the cut muzzle type.
Eight Hours - S1-E10
Character mistake: Pope tells Tom that the weapon he gives him is standard Army issue except it has a mech metal warhead. However the weapon he gives him is an RPG-7, a Soviet designed and built weapon.
Character mistake: Deni tells Anne she got a report from a scout 1,800 klicks west from here. She might have meant 18, but 1,800 doesn't seem logical. A klick is 1 kilometer (or 0.6 miles). It's unlikely a scout is over 1,110 miles away, which would put him in the middle of Texas.
Revealing mistake: When Ben is photographing the facility, it shows a camera viewfinder. The needle in the viewfinder should be horizontal to show the aperture and shutter speed is set correctly, instead it is pointing to "minus" which means the photos would be seriously underexposed.
Worlds Apart - S2-E1
Revealing mistake: When he takes some bullets out of the revolver the bullets are blanks. (00:20:50)