I could not stop laughing for a whole minute.

And while we're at it: Albus says "The Department of Secrets is not lightly defied," in reference to a Time-Turner. But earlier in the fic (and in canon), we have

There was a story she'd once heard about a criminal who had possessed a Time-Turner which the Department of Mysteries had sealed to him, in a case of extremely bad judgment as to who needed one;

And at the end: I'm not sure, but I think the missing period after "so she started climbing up the stairs toward her dorm room" was a mistake, rather than stylistic.