8. Meth Doesn't Cause Hallucinations - "Cancer Man" (1.4)
In one memorable scene in season one's "Cancer Man," Jesse Pinkman - high on crystal meth - grows overtly paranoid when two Mormon missionaries approach his house; he hallucinates and sees them as bikers of the Hell's Angels kind, hulking forwards with faces marked with death and carrying recently-sharpened machetes. It's a funny sequence, but it makes no sense at all. Why? Well, as those folk who have smoked crystal meth will know, the drug doesn't cause hallucinations. It's not a substance like LCD and doesn't provoke similar effects to the likes of magic mushrooms. And though this might seem like a minor oversight of the creative kind, it's somewhat irritating that a show built around selling crystal meth forgets one of the key things about the drug in question.