Goofs

Early on in season one they establish that modern firearms are almost never used because it is impossible to produce ammuniton for them. By season two this concept is discarded and the characters routinely use automatic weapons.

When Miles is trapped in a basement, he starts a fire to burn a hole in the roof so he can escape. As he crawls out of the hole, the edge should have scorched due to the fire.

More firearm errors: Most of the characters using fully automatic rifles fire them on full-auto. There are three notable errors involved here. First, ammunition is at a premium, so soldiers/militia would not use this setting as it consumes ammunition much faster than single shot mode. Next, modern rifles such as the M4 or M16 fire at least 700 rounds per minute on full auto. Since the magazine capacity for these is at most 30 rounds, they fire over 11 rounds per second. This would exhaust the magazine in under 3 seconds firing full auto, yet characters are shown firing for sustained periods without reloading. Finally, seasoned shooters such as militia members would realize firing full auto is the least accurate mode of fire and would avoid using it in a gun fight.

Throughout the series, a common television error involving firearms takes place. Usually whenever a gun is seen or pointed, a gun cocking sound is heard when the character is not cocking the gun or in some cases with hammerless guns that cannot be cocked. This includes after the sound has already taken place, such as when the character re-points the gun at another person. Doing so in real life with a semi-automatic rifle such as the ones used in the series would result in a round being ejected from the gun, which does not happen.

The basic premise of the series (that human beings can no longer generate electricity) defies any type of credibility.

Unless the laws of physics changed on Earth completely, there would be myriad ways to generate electricity from electromagnetism to solar panels. While it might take time to assemble the necessary elements to do this, it certainly wouldn't have taken 12 years to do so.

A recurring character error that takes place is when someone confronted by the militia fails to kill the leader of the unit that is confronting them, thereby putting the troops in disarray. For example, when Danny shoots his crossbow, he does not shoot Captain Neville. Then, after the deer hunter gives up his shotgun he shoots a soldier instead of Captain Neville. A third incident occurs when the militia is firing upon the rebels for the first time. The rebels have the sniper rifle and the militia leader is in plain view, yet the sniper does not shoot him. While Danny's incident could be attributed to a lack of combat knowledge, the same could not be said of the adults that made the same mistake.