List the mistakes, spoilers!

[MicheleLupin]

My theory with the Kreacher coming out telling the other house elves to fight for Regulus is as such:

Kreacher was tortured by Voldemort through that potion that Voldemort forced him to drink, then Regulus died by the same potion - So Kreacher must have realised something was going on by this point.

PLUS - Kreacher has known for over 3 years that Harry Potter is fighting Voldemort, and in the 7th book, he allies himself to Harry because Harry gives him the locket from Regulus. So, he must have put two and two together and realised that locket meant fighting Voldemort.

[MadEye]

These are all really good points and questions. I guess that after three times through DH I am most struck by the number of discrepancies and the lack of explanation of some fairly important points.

The business about "the trace" seemed ginned up to solve a problem that JKR had not forseen. Surely the term "The Trace" would have come up previously...there would have been no reason for it not to, as the subject of the use of underage magic has been raised many times in the books.

House elf magic would seem to be strong enough that Kreacher could have saved Regulas.

Harry thinks about calling Kreacher to him at one point, but doesn't do it because he's afraid of bringing along a DE. However, he never thinks of calling Dobby instead.

[MicheleLupin]

My assumption with Dobby is that Harry is not his master. Dobby declares himself "a free elf" - Kreacher HAS to come when he's called. Maybe Dobby wouldn't know he's being called because Harry isn't his master?

I dunno, but it gives the wondering of why Harry didn't think about it.

Plus, didn't Regulus give Kreacher the order to leave? I can't remember. I've only read DH once and I'm working my way through to it now. (on book six atm)