Good Backwards World Building: In the Harry Potter: Hogwarts Mystery mobile game, your player character must learn the charm Silencio, which causes the target to temporarily be unable to make any sound, during their fifth year at Hogwarts. During the class, it is revealed that one of the side effects of a failed Silencio charm is for the target of the spell to begin to swell uncontrollably. For players who are clever and remember the books, this will ring a bell- it was never explained why Aunt Marge in The Prisoner of Azkaban started swelling up when Harry got angry, only that he accidentally did magic. This reveal shows that in anger, his subconscious was likely trying to “shut her up”, causing a mis-cast Silencio charm, and therefore the side-effect of swelling. The reveal doesn’t change anything about the characters or their motivations, or add anything in particular to the plot. It’s just a neat bit of trivia.
Bad Backwards World Building: JKR tweets that [x] was part of [x minority group], even though there was no indication of such in the text, simply because it adds representation in hindsight.

































