The duo try to civilize a caveman so he can stay at the park; Muscle Man wants to spread his dad's ashes at the Big Rig Museum and needs Mordecai and Rigby's help getting there.

Starring:

Mark Hamill, J.G. Quintel, William Salyers, Roger Craig Smith, Jeff Bennett, Janie Haddad Tompkins, Sam Marin

Genre:

Adventure, Animation, Comedy