The Thing and I: The kids hear something in the attic one night, and go to investigate. They find an empty cage, and ask their parents about it. Eventually, they reveal that Bart has an evil twin called Hugo who was locked in the attic. However, Hugo escapes and captures Bart when the rest of the family go out to look for Hugo. Dr. Hibbert manages to capture Hugo, but discovers that Bart's scar is on the wrong side and so Bart must be the evil left twin.
The Genius Tub: Lisa makes a science project to prove the bad effects of soda drinks on teeth. However, it comes to life when the tooth is shocked with static electricity. After Bart attacks Lisa's experiment, the miniature world shrinks Lisa and brings her into their world to protect them from Bart. However, Bart takes the mini world to the Science Fair and wins first prize.
Citizen Kang: Kang and Kodos return to Earth and kidnap and impersonate Bill Clinton and Bob Dole so they can win the election. Homer knows about this and tries to warn everyone, but there are no other candidates. Kang wins and enslaves the world.