Milo Coy

Stan

Jack Black

Grown Up Stan (voice)

Zachary Levi

Kranz

Glen Powell

Bostick

Josh Wiggins

Steve

Lee Eddy

Mom

Bill Wise

Dad

Natalie L'Amoreaux

Vicky

Jessica Brynn Cohen

Jana

Sam Chipman

Greg

Danielle Guilbot

Stephanie

Larry Jack Dotson

Grandfather

Mona Lee Fultz

Grandmother #1

Jennifer Griffin

Grandmother #2

Holt Boggs

Sam The Rocket Man

Reese Armstrong

Tony

Samuel Davis

Joey

Nick Stevenson

SIMSUP

Brian Villalobos

David DeLao

Avery Joy Davis

Lisa

Christian Moran

Hoodlum

Nicholas Andrew Rice

NASA Control Man

Keslee Blalock

Astro World Kid

John Kaler

Nasa Mission Control

Brent A. Riggs

Service Station Attendant

P. Michael Hayes II

Simsup

Flint Nattinger

Laughing Boy

Natalie Joy

Music Class Teacher

Suzanne Deal Booth

Science Teacher

Chris Olson

Principal Cowan

William Carroll

Abominable Snowman