An unusually serious example: In the The Sarah Jane Adventures episode "Mona Lisa's Revenge", K9 zaps the Mona Lisa and the Abomination back into paintings-along with himself. Next episode, everything's back to normal with no explanation.
That wasn't the real K9; he'd come from a picture as well (one drawn by Clyde).
Pulled this:
That wasn't the real K9; he'd come from a picture as well (one drawn by Clyde).