Rowling said in an interview in 2005 (lexicon.org/source/interviews/tlc/">TLC) that since she doesn’t re-read her own books, “there are thousands of fans who know the books much better than I do.” I suppose that’s why she admitted to using the Harry Potter Lexicon as a reference while writing the books. We fans do notice absolutely everything. One thing fans noticed in this chapter was an inconsistency in the appearance of the Prefect’s badge that Ron finds in his envelope from Hogwarts. Here’s how Rowling describes it: George leapt forwards, seized the envelope in Ron’s other hand and turned it upside-down. Harry saw something scarlet and gold fall into George’s palm. ‘No way,’ said George in a hushed voice. ‘There’s been a mistake,’ said Fred, snatching the letter out of Ron’s grasp and holding it up to the light as though checking for a watermark. ‘No one in their right mind would make Ron a prefect.’ Ron, who still had not said a word, took the badge, stared at it for a moment, then held it out to Harry as though asking mutely for confirmation that it was genuine. Harry took it. A large ‘P’ was superimposed on the Gryffindor lion. He had seen a badge just like this on Percy’s chest on his very first day at Hogwarts (OP9). So it’s red and gold with a large P superimposed on the Gryffindor lion. But here’s how that badge was described in book one: The oldest boy came striding into sight. He had already changed into his billowing black Hogwarts robes, and Harry noticed a shiny silver badge on his chest with the letter P on it (PS6). In 1991, it was silver, not house colors as it was in 1995. Now we might explain this away by suggesting that the badges had been redesigned in the intervening years, except that Order of the Phoenix states quite clearly that Harry had seen a badge “just like this one on Percy’s chest” four years before. So it’s definitely a mistake, what fans called a “flint” back in the day. A “flint” was a genuine error, so called because of the famous mistake Rowling made where she left lexicon.org/character/flint-family/marcus-flint/">Marcus Flint in the story for one book too many, making him an “eighth year” student in book three. When asked about this error in a February 2000 interview (lexicon.org/source/interviews/sch1/">Sch1), Rowling joked about it: In the first book you said Slytherin house Quidditch captain was sixth year Marcus Flint. If there are only seven years of Hogwarts, why is he in the third book? Rowling’s answer was “He had to do a year again! :-)” Because of that, for many years after fans used the term “flint” for an error or inconsistency. The Prefect’s Badge Inconsistency received an official fix, however. In the set of lexicon.org/edits-changes-text-ps/">corrections issued by Bloomsbury in 2004, the following change was dictated for the text of book one: “Harry noticed a shiny silver badge on his chest with the letter P on it” was changed to  “Harry noticed a red and gold badge on his chest with the letter P on it.” So that “flint” is no longer a “flint.” And modern readers will never know any different. But it’s fun to know that fans back in 2000 caught enough of those little errors to have their own Harry Potter fan term for them.