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)
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)
Continuity mistake: When Hank is standing between the ATM and the pumps at the gas station, the shadow cast by the roof over the pumps shifts between shots. The shot from away, taken next to the pole with the Indian logo was taken earlier in the day, casting a long shadow. The other shots have a higher sun which has moved by several hours.
Continuity mistake: When Walt is talking to Saul near the start, we see him unbalance the scales on the table in front of him then lean back. Camera cuts to Saul for a few seconds then shows Walt from behind Saul. In this angle, the scales are now balanced. (00:16:50)
Continuity mistake: While Walt is out of his car and arguing with the police officer, there are other cars visible in the far distance behind him. The cars appear and disappear in between shots, there isn't time for them to pass and we don't hear them pass. (00:03:30)