Oh, well, if River's leaving, no point in hanging round here.
She's nicked Spike's plan of showing off over the body of their enemy, but he doesn't bear malice. He does, however, bear knives. He leaves one through the magician's palm and one in his vocal chords -- chant now, supercilious bastard -- on his way to the door.

He's whistling something that one might, if one were an optimist, recognize as "can't catch me, I'm the Gingerbread Man..."