Stewie builds a DNA-altering machine that will allow him to remain smart forever, but the invention has the adverse effect and he instead transforms into what he should have always been - an actual baby.
Seth MacFarlane
Peter Griffin / Brian Griffin / Stewie Griffin / Glenn Quagmire / Tom Tucker (voice)
Alex Borstein
Lois Griffin / Tricia Takanawa / Loretta Brown / Barbara Pewterschmidt (voice)
Mila Kunis
Meg Griffin (voice)
Seth Green
Chris Griffin (voice)
Mike Henry
Cleveland Brown (voice)
Patrick Warburton
Joe Swanson (voice)
Brett Gelman
Escape Room Guy (voice)
Mike Desilets
(voice)
Judy Greer
Bozo's Client / Sylvester Stallone's Assistant (voice)
Robert Wu
Korean General (voice)
Artie Johann
James Taylor (voice)
Steve Callaghan
Audience Member / Target Employee (voice)
Dee Bradley Baker
Gremlin Stewie (voice)
Ralph Garman
Man (voice)
Rachael MacFarlane
Waitress (voice)
Alec Sulkin
(voice)
Kevin Michael Richardson
Jerome (voice)
Jennifer Tilly
Bonnie Swanson (voice)