Any basic first-year knows one generic rule about Hogwarts: you can't apparate onto the grounds of the School of Witchcraft and Wizardry.
For the two readers who have never read or seen HP, apparition is a ~magically~ instantaneous form of teleportation. The rule essentially prevents evil wizards (i.e. Voldemort) from just popping up on the Hogwarts campus any ole time they please. There is, of course, one exemption: Headmaster Dumbledore. However, The Crimes of Grindelwald is supposedly set three decades before his appointment, so this info is rather useless.
Anyhoo, in the new trailer for Fantastic Beasts: The Crimes of Grindelwald (which was released on Tuesday), a group of high-powered Ministry wizards apparate to — you guessed it — Hogwarts. This was not lost on Potterheads, who took to Twitter to call out the error.
However, some fans argued the snippet may not be a mistake at all. It's possible the no apparition rule was made only after (or because of?) Grindelwald.
It should be noted that Mother Rowling wrote the screenplay for this film. Sure, she's bound to make mistakes — she's only human, after all — but if we were to guess, we think the "error" will somehow be explained in the film.
I guess we'll all have to wait until November to find out.