1. They are able to literally grow bones back from nothing but can’t fix Harry’s eyesight so he doesn’t need glasses.
2. Wizards don’t understand things like phones, muggle clothes, or muggle money. They live in a place where 99% of the population is muggles. You would think they would pick up some basic understanding.
5. That none of the kids in Harry’s first year knew about the sorting hat. Literally not one. Not even Malfoy. Not even Ron with his 5 brothers going before him as well as his parents. Yet in the end of the last book, Harry is openly discussing the event with his son.
6. Even with so much technology available, they choose to remain medieval with everything in their lives!
7. What happened to Harry’s grandparents? Lily and James were in their very early 20’s when he was born. His grandparents could be anywhere from 40-60 years old. You’re telling me that not one was still alive?
8. The Knight bus. It’s set up with beds instead of seats, but it pops around the country by magic. If it is clearly moving far faster than a regular bus why would it have the longer term piece of furniture?
9. Subjects at Hogwarts. They’re taught about Herbology, Defense Against the Dark Arts, Potions, etc.. But what about local and Universal History? Geography? Social Studies. Literature. Math. Any Sciences at all? If they’re not taking any of those classes, Hogwarts’ students are very much at a disadvantage against a world that is slowly closing in on them (the human world, I mean).
10. Ron should not have been able to tell Dobby where Bill’s house was, since he wasn’t the secret keeper. Massive plot hole.
11. Accio being a fourth-year spell. You can tell that this is only because JKR didn’t think of it til GoF, because this incredibly simple yet useful spell appears exactly zero times in previous books.
12. I don’t understand why Dumbledore tolerated the way the Dursleys treated Harry so poorly. Even if he didn’t want Harry to know that he was a wizard-world rock star, he might have had Hagrid drop by one day when Harry wasn’t around to have a word with Vernon.
13. At Slughorn’s Slug Club meetings, Hermione brings up her father being a dentist, which gets confused stares from the students and Slughorn. Yet, in the Chamber of Secrets a clock in the Weasley house can be seen, each hand with a family members’ face, and many indications of where they might be at any given moment. One of those places is dentist.
14. What was the deal with unbreakable vows? And what stopped dumb teenagers from making them? There is no way that not a single dumb teenage magic couple didn’t make an unbreakable vow to “love each other forever.
15. Hagrid says there wasn’t a bad wizard that didn’t come out of Slytherin, so didn’t anyone think that maybe the problem was that they were putting all the problem children with other problem children and locking them in a dungeon during their formative years? Of fucking course they turned out evil. If your only option for friends are Crabbe and Goyle and Malfoy, and everyone looks at you like you’re a criminal, and you LIVE IN A DUNGEON maybe you’ll become a criminal.
18. Nobody at Hogwarts ever exercises (hell, their only sport is them sitting practically still), and the great hall has unlimited fattening food, but everyone is super skinny. Especially Harry, who grew up underfed, would probably gorge himself and gain at least a few pounds. But no, everyone is super thin.
19. I know I’m late to the thread, but I’ve never understood something about the Triwizard tournament. For the spectators, two of the three tasks must be super boring. Here, watch these people jump in a lake. Now wait. Now, watch these people disappear into a hedge maze. Now wait. Whee. Sounds like fun to me.
20. JK Rowling admits she’s bad at math, but like how many people go to Hogwarts? If there are really only 10 students per house per year, that’s only 280 people. But she describes hundreds, sometimes thousands of kids. The only compelling argument I can think of is that there was a huge demographic shift after Voldemort was “defeated” and a lot more people had babies so the years right after Harry have a lot more students. I honestly think she just hadn’t figured out how many students it was.
22. Time-turners. Everyone acknowledges the massive potential ramifications of using a time-turner improperly to the extent that they’re not allowed to be used by anyone. But an exception is made for teenagers – arguably the most irrational users conceivable – with raging hormones and not-yet fully developed brains. Probably not a good policy.
23. The way wizards just didn’t wear robes in the movies.
24. Why was Dumbledore chess mastering the whole thing? Did Dumbledore specifically set up the whole series of events in a giant decade long trap? Why did he train Harry as a magical child soldier? Why did he do everything at arm’s length? Dumbledore had the magical equivalent of a nuke with the Elder Wand and invisibility cloak. He very well could have beaten every death eater individually, picking away at their numbers. The Death Eaters still have families and day jobs and go to the bathroom. They aren’t in a huge magical army so they could face off against a superior opponent. There wasn’t a reason to go all cloak and dagger. Dumbledore is hideously powerful, had access to immortality and had 2/3 of the most powerful magical items (and all of the useful ones) from death himself. So why go through so much trouble?
27. Where do the pure blood kids go before Hogwarts/secondary school? Do they have a wizarding primary school? Are they homeschooled? They don’t go to muggle schools because they know jack shit about the muggle world I need a n s w e r s.
28. Love potions being legal. Gotta be the biggest bunch of date rapists ever.
29. Kids from across the UK have to get to London to get on the Hogwarts Express which takes them up to Scotland. Surely a kid from Scotland or even Manchester doesn’t have to spend hours getting down to London to then go back up to Scotland.
30. That Hogwarts was supposedly one of the safest places in the world.