Connections

the original cartoon is used in the opening credits

clips used (verified in end credits)

Jay Leno makes a joke about Underdog on his show.

UnderDog's fever dream where his powers awaken is a reference to the fever dream Peter Parker has in Spider-Man (2002).

Has the cliche spaghetti scene

Underdog suprises a cat burglar by standing above him on the building. Underdog's flight with Polly mirrors Superman's flight with Lois Lane.

In Superman II, Superman gives up his powers to be with Lois and fights three Kryptonians with the same powers he had. In Underdog, Underdog gives up his powers to save his family and fights three German shepards with the same powers he had

The scene where Cad dresses up as an old lady spoofs the scene in Spider-Man 2 where Aunt May is trapped at the window after Dr. Octopus attacked the bank.

underdog goes all the way up into the atmosphere and then crashs on re-entering. this entire scene is and spoof/homage to the end of superman returns.