Tim Allen
Jason Nesmith
Sigourney Weaver
Gwen DeMarco
Alan Rickman
Alexander Dane
Tony Shalhoub
Fred Kwan
Sam Rockwell
Guy Fleegman
Daryl Mitchell
Tommy Webber
Enrico Colantoni
Mathesar
Robin Sachs
Sarris
Jed Rees
Teb
Justin Long
Brandon
Missi Pyle
Laliari
Patrick Breen
Quellek
Jeremy Howard
Kyle
Sam Lloyd
Neru
Rainn Wilson
Lahnk
J.P. Manoux
Excited Alien
Dian Bachar
Nervous Tech
Heidi Swedberg
Brandon's Mom
Kevin McDonald
Announcer (as Kevin Hamilton McDonald)
Kaitlin Cullum
Katelyn
Jonathan Feyer
Hollister
Corbin Bleu
Young Tommy
Isaac C. Singleton Jr.
Sarris' Guard
Joel McKinnon Miller
Warrior Alien
Todd Giebenhain
Teen in the Bathroom #2
Jerry Penacoli
Reporter
Jennifer Manley
Shy Girl
Matt Winston
Technician #1
Marcio Rosario
Sarri's Guard (uncredited)
Morgan Rusler
Fan #2