We learn that there are four types of poisoners who target multiple victims:
True Believer - political terrorist/religious cult.
Extortionist - product tamperer, holds the business hostage in exchange for money.
Prankster - usually younger offender who doesn't mean any harm.
Avenger - someone with a personal vendetta.
We also learn that with the exception of the prankster, these types of multiple-victim poisoners usually test their methods out on a small, random group before moving on to their larger targets.
We learn that botulism is the deadliest form of toxin known to man. It paralyzes its victims and, without an antitoxin, will literally choke its victims to death within 36 hours.
Botulism is found in the popular anti-aging treatment Botox.
We learn that Hotch is still a card-carrying lawyer when he offers to take the unsub's case.
Reid: (after one of the victims dies of botulism) The test run is over.
Gideon: Confucius told us, "If you go out to seek revenge, dig two graves."
Garcia refers to Morgan as Cochise; this is a reference to the Apache leader of the same name who resisted both Mexican and American attempts to overtake the area in which he and his people lived (the Mexican region of Sonora, New Mexico, and Arizona).