The trivia items below may give away important plot points.
The title of this episode refers to Kate Argent, Allison's aunt, who broke the hunter code years before when she torched Derek's entire family. Kate pays the ultimate price for this breach at the end of the episode.
The final shot of the episode (and season) of Scott and Allison sitting on the roof looking at the moon is a digital composite. The roof in reality was far too steep and dangerous to have the show's leads sit on it, so they were added in afterwards.