Things from the show that don't appear to be in the movie (many of these gathered from the Wikipedia entry on the show:
- Underdog's alter ego is Shoeshine Boy, and that's his profession. He doesn't belong to a kid, and he's supposed to be a parody of Superman/Clark Kent.
- TV Underdog had to take pills to give him his powers, and his powers would wear off over time. Often this would be used as a vulnerability...he'd be trapped and without his pills to get back his super powers. Eventually they edited out those scenes in syndication because of the obvious drug parallel that might have been ok when the show first aired in the mid 60's. But his powers didn't come from a "freak accident" like in the movie.
- Underdog almost always spoke in rhyme, hence his usual line, "There's no need to fear, Underdog is here!" And, "When Polly's in trouble, I am not slow...So it's hip! hip! hip! and away I go!"
- Underdog wears pants. Because otherwise he's naked!
- Underdog wears boots
- Underdog has a very distinctive voice, and it's certainly not that of Earl from My Name is Earl.
- Underdog is usually cross-eyed...it's pretty distinctive
- The TV show was usually presented in parts, so you didn't get a complete story in one episode. Obviously you can't do that with a movie.
- The cheap animation was another distinctive trait...the movie is almost the polar opposite.