* The Joker is a goldmine of these during his limited time in the series. There's his first appearance in the Christmas issue - stealing a family's Christmas presents, while quoting the Grinch, no less.
* A minor one, but Catwoman - when grabbed by a Ivy-controlled Bruce Wayne - actually lets out a, "Mrow!" of surprise.
* Calendar Man and Holiday's holiday-themed tête–à–tête near the end.