Buffy: The Vampire Slayer - Where Did the Ashes Go?
After Glory has kidnapped Dawn and has brought her to the site where she will use her as "the key," she (or one of her minions) puts ashes on Dawn's forehead in order to begin the ceremonial process. However, when Glory and Ben start having their multiple personality argument, the ashes begin to appear and disappear from shot to shot. I didn't notice it the first time I saw the episode, but I noticed it during the second viewing.
Second-to-last episode of Season 5
on 07-27-2001 and