Meanwhile, here is the synopsis from tv.com.
I loved seeing Rachel giving out the candy because she's beginning to have motherly instincts and how she showed up as "a woman who bought an expensive dress she won't be able to wear in a few months" (when her pregnancy started showing). Monica had asked everyone to wear costumes.
Monica thinks Joey didn't dress up either, but Joey says he's dressed as Chandler.
Below are images from the episode:
EDIT: I just added Disc One of Season 8 to slot one of my Netflix queue.