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
Patrick Breen ... Quellek
Missi Pyle ... Laliari
Jed Rees ... Teb
Justin Long ... Brandon
Jeremy Howard ... Kyle
Kaitlin Cullum ... Katelyn
Jonathan Feyer ... Hollister
Corbin Bleu ... Young Tommy
Wayne Pere ... Lathe
Sam Lloyd ... Neru (as Samuel Lloyd)
Bill Chott ... Fan #1
Morgan Rusler ... Fan #2
Gregg Binkley ... Fan #3
Brandon Michael DePaul ... Fan #4 (as Brandon Michael de Paul)
Paul G. Kubiak ... Fan #5
Gregory Colbrook ... Fan #6 (as Greg Colbrook)
Jennifer Manley ... Shy Girl
John Patrick White ... Teen in the Bathroom #1
Todd Giebenhain ... Teen in the Bathroom #2
J.P. Manoux ... Excited Alien
Dan Gunther ... Navigator
Matt Winston ... Technician #1
Brandon Keener ... Technician #2
Dian Bachar ... Nervous Tech
Rainn Wilson ... Lahnk
Susan Egan ... Teek (scenes deleted)
Heidi Swedberg ... Brandon's Mom
Isaac C. Singleton Jr. ... Sarris' Guard
Jerry Penacoli ... Reporter
Joel McKinnon Miller ... Warrior Alien
Kevin McDonald ... Announcer (as Kevin Hamilton McDonald)
Daniel Parker ... Alien Fan (as Daniel T. Parker)
Dawn Hutchins ... Inventory Clerk
Joe Frank ... Voice of the Computer (voice)
Larry Richards ... Thermian Greeter #1 (as Lawrence Richards)
Mic Tomasi ... Thermian Greeter #2