At the end of the episode, Dan comically uses a handheld mirror to see if Darlene is still breathing. He actually uses the back of the mirror (which is non-reflective) to check her breath and the reflective side is facing the camera so that the audience knows that is a mirror.
In the very last scene of the episode "Darlene Fades to Black", the shadow of a person can be seen behind the front curtain.