Character mistake: When Walt and Gretchen are talking about the elements in the body, they list hydrogen, oxygen, carbon, nitrogen, calcium, iron, sodium, and phosphorus. The percentage is short and she says "supposedly that's everything." But they don't count elements like sulfur (which has a greater abundance than sodium), potassium, chlorine, and magnesium. Even as college students, they would know those elements are in the body.
Revealing mistake: At the end of the episode when Tuco shows up at Walter's house in the backseat of Jesse's car, he tells Walter to get in. As they drive off, the shot pans out to show the street sign across from Walter's house. The sign says Piermont, which is the real name of the street. In the show, the Whites live on Negra Arroyo Lane. (00:48:00)
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)
Plot hole: Preparing to steal methylamine from the train, Walt, Jesse and Mike measure off a predetermined distance from the railroad crossing, which happens to coincide with a handy arroyo, where they bury their tanks. Problem is that they couldn't have known that distance (calculated by knowing the position of the methylamine tanker car in the train) until Lydia told them. But she didn't call that info in until the night after they'd already buried the tanks.
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.
Character mistake: When Hank is brought to the hospital with gunshot wounds, the ambulance and its two EMTs are met outside by two doctors. One doctor says "Let's get him two grams of oxygen. What's his hemoglobin?" This episode's technical adviser was perhaps away for this scene. How much exactly is two grams of oxygen? Orders for administering oxygen would be given in liters, such as two liters per minute (LPM). The line is presumably meant to be 'two liters of oxygen'. (00:02:25)