Chemist Mickey concocts a super strength potion, called the "Courage Builder", that turns turns the food chain on its head, allowing underdogs to turn against their tormentors (a fly manages to turn against a spider, a mouse against a cat, the cat against Pluto, and Pluto against dogcatcher Pete).
- Mickey Mouse (voiced by Walt Disney)
- Pluto (voiced by Pinto Colvig)
- Pete (voiced by Billy Bletcher)
- Cat (voiced by Clarence Nash)
- Spider (voiced by Clarence Nash)
- Good Morning, Mickey, episode #22
- Mickey's Mouse Tracks, episode #41
- Donald's Quack Attack, episode *88
- The Ink and Paint Club, episode #1.55: "Oooh! Scary!"
- Walt Disney Cartoon Classics: Limited Gold Editions: Mickey
- Mickey's Magical World
- The Spirit of Mickey
- Donald and Company
- The short's title card apparently shows a worm attacking a bird. Such animals never appeared in the short itself.
- The cat's lives-represented-as-nine-angels gag shown before Mickey sprays the cat so that it attacks Pluto was previously seen in Pluto's Judgement Day during the Uncle Tom sequence.
- A spider resembling the one in this short appears as the first boss in the Sega Genesis game World of Illusion Starring Mickey Mouse and Donald Duck.
- The music performed in this short is actually one of Franz von Suppé's most notable work, Leichte Kavallerie (Light Cavalry).