Based on "Gilligan's Planet" maybe?
By any chance was this story based on "Gilligan's Planet"?
It would explain why the characters are so dumb I couldn't finish watching it.
Storyline
An animated re-make of the famous TV series "Gilligan's Island." The gang of castaways build a spaceship and leave planet Earth behind. Of course, they get marooned on an uncharted planet, where they encounter bizarre space creatures and other hazards of extraterrestrial living.