Warning: this one contains a spoiler that doesn't get revealed until a few books later. When McCoy mentions that only four people knew about the location of the training camp, he forgets about one person who almost certainly knew. Wizard Peabody, who's always in the background, rarely noticed. He handles all the White Council's paperwork, so it's pretty much guaranteed that he knew about the training camp. But since he's seen by everyone as a paper-pusher and is basically ignored when he's not needed, McCoy doesn't even think of him when listing potential traitors.
Alternately, he ensured McCoy wouldn't notice him with a little mind-nudge.
It apparently never even occurred to Greene or Rick to ask Molly how old she was before questioning her. Molly is routinely described as tall even by Harry, and both her parents are pretty tall also. Not too surprising that she'd look like a young adult, not a minor, at first glance, especially decked out a la Goth for a horror convention.
I realize it's basically a send up of campy horror films, and you're not supposed to think too much about it, but how the hell did Hammerhands strap hammerheads onto the stumps of his hands...when he had no hands to do it with?
