Factual error: Hydrofluoric acid is so dangerous that no high school chemistry lab in the US would have a thimble full of the stuff around, let alone gallons. While it's incredibly toxic it's also a very poor choice for getting rid of bodies, which Walt would know.
Factual error: When the planes crash over Albuquerque, when the bear is falling towards Walt's house, there is a quick shot of Albuquerque suburbia and mountains. Two major streets are visible, the one on the right is Eubank Blvd and the one in the lower left is Wyoming Blvd, both which run north and south through the city. This means the shot is facing north. There are no mountains immediately north of Albuquerque as shown. The closest mountain range, the Sandia Mountains, are on the east side and wouldn't be in that shot. The closest mountain range in the north are the Jemez Mountains, which are 40 miles away. They would barely be visible in that shot (they would look like blue hills in the distance).
Factual error: The final scene of the episode, the cousins are hiding with other migrants amid a farm truck's bales of straw. One of the migrants claims they are in Texas. However, the mountains in the distance are the Manzano Mountains which are just several miles southeast of Albuquerque, more than 200 miles away from the border with Texas and Mexico. The migrant claims he has gone through this route 3 times, so it is unlikely this would simply be a character mistake.
Factual error: As demonstrated in the earlier scene where Leonel shot the truck driver/arms dealer, bulletproof vests do not make the wearer immune to bullets. Bulletproof vests are only designed to stop penetrating injury- they do not counteract the high energy of an impacting round, which can easily break ribs and cause internal injury. When Hank empties Leonel's dropped gun into Marco, Marco is barely staggered despite the fact that he just took five rapidly fired bullets in quick succession to his upper chest. That many hits at such close range in such a small zone would have, at minimum, shattered several of Marco's ribs and potentially punctured one or both of his lungs - both critical and incapacitating injuries on their own. As a result, Marco should have been unable to lift his gun to shoot Hank twice in the chest, much less swing an axe. Additionally, at least one bullet appears to strike Marco's clavicle and upper shoulder- both areas that are not protected by the vest. (00:44:00 - 00:45:00)
Factual error: In the opening scene for the episode, a character commits suicide by electrocuting themselves with a defibrillator. The device used was an AED (automated external defibrillator) which analyses the electrical rhythm of the heart and only delivers a shock when the heart rhythm is ventricular tachycardia or ventricular fibrillation. In this case, the device would not have delivered a shock as the person did not have both ECG electrodes attached and therefore would not have detected a cardiac rhythm. The person would also have had a normal heart rhythm.
Factual error: When going over the logistics of the plan to kill the ten men in prison, Jack tells Walt that killing Osama Bin Laden was less complicated. Breaking Bad takes place over a period of two years, beginning with Walt's birthday in 2008, and ending on his birthday in 2010. Bin Laden wasn't killed until May of 2011. (00:15:23)