John Cho as Harold Lee

Kal Penn as Kumar Patel

Paula Garcés as Maria

Neil Patrick Harris as Neil Patrick Harris

David Krumholtz as Seth Goldstein

Malin Åkerman as Liane

Kate Kelton as Christy

Brooke D'Orsay as Clarissa

Steve Braun as Cole

Fred Willard as Dr. Willoughby

Rob Tinkler as J.D.

Bobby Lee as Kenneth Park

Anthony Anderson as Burger Shack Employee

Ethan Embry as Billy Carver

Eddie Kaye Thomas as Rosenberg

Ryan Reynolds as Male Nurse

Christopher Meloni as Freakshow

Boyd Banks as E.R. Patient

Siu Ta as Cindy Kim

Gary Anthony Williams as Tarik

Dov Tiefenbach as Hippie Student

Dan Bochart as Extreme Sports Punk #1

Mike Sheer as 'I'm So High' Kid

Christopher Thompson as 'Don't You Wanna Be Cool' Kid

Angelo Tsarouchas as Mean Tollbooth Guy

Albert Howell as Security Guard

Errol Sitahal as Dr. Patel

Shaun Majumder as Saikat Patel

Rick Sood as Indian Cashier

Sandy Jobin-Bevans as Officer Palumbo

Brad Borbridge as Officer Martone

Frank Spadone as Officer Reilly

Jordan Prentice as Giant Bag of Weed

Gary Archibald as Nathaniel Brooks

John Boylan as Officer Brucks

Dan Warry-Smith as White Castle Teenager

Thea Andrews as Female Anchor

Jamie Kennedy as Creepy Guy (uncredited)

Jon Hurwitz as Tony (uncredited)

Hayden Schlossberg as Hayden (uncredited)