In the series finale of Planet Sheen, we see that Sheen does not return back to Earth.But if you saw the Jimmy Neutron episode The Tommorow Boys, we see in the future, Sheen is back on Earth! It is possible that he did fix his rocket and returned home (but forgot all about Zeenu),or Jimmy Neutron found out that Sheen was gone, so he could of went in the past to stop him from building the rocket (but he had to do it after Banana quest).However,the idea of Planet Sheen wasn't thought of yet, so that episode was possibily canon, so sadly,Sheen could be stuck on Zeenu FOREVER. I sure hope Sheen DOES get to go home. But he does not the show is non canon. <- refer to the future episode none of planet sheen did happen. Hence forth its just non canon.