The Simpsons: 700th Episode Sneak Peek Check out a sneak peek of the 700th episode of The Simpsons, which will air this Sunday on Fox. Bill Plympton will return for an all new couch gag. Check out the video and more information below. Upcoming Episode Information: A secret about Flanders’ past is revealed and a never-before-seen room is discovered in the Simpson home in the …