Spy Kids 3

Spy Kids: Sylvester Stallone!!! How Did You Get In Here?

Sylvester Stallone: Oh Don't mind me kids i was just lookin for a movie to be in. ever since my Wife divorced me and took most of my money
Spy Kids: Oh Well.... You Can Be In Our Next Movie!
Sylvester Stallone: YES FINALLY BEAT THAT ARNOLD!!!

and that is the story of why Sylvester Stallone was in Spy Kids 3

Why Isn't Arnold Schwarzenegger In Spy Kids 3?