Another example would be Draco, to Harry, in Chapter 7:
"The courts use Veritaserum, but it's a joke really, you just Obliviate yourself before you testify and then claim the other person was Memory-Charmed with a false memory. If you've got a Pensieve, and we do, you can even get the memory back afterward."
And that's a very good point. I can't quite tell whether Dumbledore picked up on the mistake that Lucius made, just from Harry's memory - the only reaction we are directly told about is
Dumbledore's face had grown more remote as Harry went on, and at the end there was a look of ancientness about him, a sternness in the air.
"Well," said Dumbledore. "I suggest you take the best of care that the heir of Malfoy does not come to harm, then. And I will do the same." The Headmaster was frowning, his fingers drumming soundlessly through the inky black surface of a plate inscribed with the word Leliel. "And I think it would be most extremely wise for you to avoid all interaction with Lord Malfoy henceforth."
and then the conversation switches tracks. If Dumbledore did get the subtext just from Harry's (described, offscreen) verbal recollections, then the lack is just a minor puzzling detail; but if he didn't, when he most certainly could have from the inhumanly perfect reproduction of a Pensieve, failing to use one seems a critical flaw.
(The HPMOR discussion thread after this one is here.)
The previous thread is over 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 latest chapter as of 09/09/2011 is Ch. 77.
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, eight. 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: