In "Which Came First?", when a field trip across the desert is ruined by the school bus' flat tire, Billy, Mandy and Grim go into a cave infested by giant mutant chickens. In "Substitute ...

Cast: Grey Griffin, Greg Eagles, Richard Steven Horvitz, Dee Bradley Baker, Jane Carr, Debi Derryberry, Paul Eiding, Martin Jarvis, Rachael MacFarlane, Vanessa Marshall, Lara Jill Miller, Renee Raudman