The story begins with a normal, bumbling everyday watchdog beagle named Shoeshine who gets exposed to a substance that gives him the powers of a superhero. And not to mention the ability the speak during an accident. He is adopted by a security guard - an ex-cop, who's a widower with a 12-year-old moody son, Jack Unger. Shoeshine uses his superpower to protect his love and the citizens of Capitol City from the evil Simon Barsinister. Underdog dedicates himself to good, quickly becoming revered as a superhero, but ultimately it will take the combined efforts and understanding of Underdog, Jack, Dan, Molly, and Polly to defeat Barsinister and save Capital City from destruction.

General Mills breakfast cereal products are seen in the Unger household. The "Underdog" (1964) cartoon series was created by General Mills' ad agency to help promote their products.

[from trailer]


Shoeshine Boy:
Y'know, you never see dogs hurting each other for money.


Jack:
You never see people sniffing each other's butts.


Shoeshine Boy:
Touché.

Revealing mistakes: When Underdog is re-entering Earth’s atmosphere he starts to burn up, when he crashes back to earth and Jack rushes to him and picks him up, you can clearly see it is a puppet.

Written by W. Watts Biggers, Treadwell Covington (as Treadwell D. Covington),
Joseph Harris (as Joseph B. Harris), Chester Stover (as Chester A. Stover)