That duel was a faked show, it never really happened, at least not in the way people were led to believe it did.
You know, I didn't realize until just now what it was that seemed off about Draco's account of the duel with Grindelwald. He said (quote) "there’s no way two wizards would be so exactly matched that they’d fight for twenty whole hours until one of them fell over from exhaustion", and used this improbability as evidence that the fight had been staged.
Fact from canon that I don't believe has been mentioned in MoR (and thus may not be MoR canon): Gur Ryqre Jnaq unf gur negvsnpg-yriry cebcregl bs 'haorngnoyr va pbzong', ohg jvryqref pbhyq or xvyyrq ...
Update: Discussion has moved on to a new thread.
The hiatus is over with today's publication of chapter 73, and the previous thread is approaching the 500-comment threshold, so let's start a new Harry Potter and the Methods of Rationality discussion thread. This is the place to discuss Eliezer Yudkowsky's Harry Potter fanfic and anything related to it.
The first 5 discussion threads are on the main page under the harry_potter tag. Threads 6 and on (including this one) are in the discussion section using its separate tag system. Also: one, two, three, four, five, six, seven. The fanfiction.net author page is the central location for information about updates and links to HPMOR-related goodies, and AdeleneDawner has kept an archive of Author's Notes.
As a reminder, it's often useful to start your comment by indicating which chapter you are commenting on.
Spoiler Warning: this thread is full of spoilers. With few exceptions, spoilers for MOR and canon are fair game to post, without warning or rot13. More specifically: