Tim Allen
Jack Sheppard
Courteney Cox
Marsha Holloway
Chevy Chase
Dr. Grant
Spencer Breslin
Tucker Willams / Mega-Boy
Kevin Zegers
Connor Shepard / Concussion
Kate Mara
Summer Jones / Wonder
Michael Cassidy
Dylan West / Houdini
Ryan Whitney Newman
Cindy Collins / Princess
Rip Torn
Larraby
Cornelia Guest
Cindy's Mom
Ashton Moio
Halloween Bully
Thomas F. Wilson
Dylan's Teacher
Ridge Canipe
Mean Bully
Danny McCarthy
Meaner Bully
David L. Lander
Wendy's Employee
Lauren Sánchez
Reporter
Willie Garson
Dick
Zoe Doyle
Researcher
Kendra Rose Montagna
Cheerleader
Aaron Abrams
Corporal Lipscombe (uncredited)
Nick Baga
Fat Swimmer (uncredited)
Alexis Bledel
Ace (uncredited)
Darryl Dinn
Lab Researcher (uncredited)
Hunter Aarniokoski
Prince
Jane Hajduk
Researcher Taylor
Tommy Chang
Martial Arts Instructor
Tim Nasiopoulos
Large Agent
Deanna DeLisle
Cheerleader
Meg Anderson
Cheerleader
Stacey Alfano
Stefanie (uncredited)
Allison Gordon
Girl with Big Hair (uncredited)
Sadey Paige Nifong
Kid In Pool (uncredited)
Andrea Savo
Carmen / Big haired Latina (uncredited)