Joseph Gordon-Levitt as Adam Lerner

Seth Rogen as Kyle Hirons

Anna Kendrick as Katherine McKay

Bryce Dallas Howard as Rachael

Philip Baker Hall as Alan

Serge Houde as Richard Lerner

Andrew Airlie as Dr. Ross

Matt Frewer as Mitch

Peter Kelamis as Phil

Jessica Parker Kennedy as Jackie

Anjelica Huston as Diane Lerner

Sugar Lyn Beard as Susan

Donna Yamamoto as Dr. Walderson

Yee Jee Tso as Dr. Lee

Sarah Smyth as Jenny

Daniel Bacon as Dr. Phillips

P. Lynn Johnson as Bernie

Laura Bertram as Claire

Matty Finochio as Ted

Marie Avgeropoulos as Allison

Luisa d'Oliveira as Agabelle Loogenburgen

Veena Sood as Nurse Stewart

Andrea Brooks as Attractive Woman #2

Beatrice King as Pretty Girl

Chilton Crane as Mother on the Bus

Lauren Miller Rogen as Bodie

Jason Vaisvila as Cute Guy with Dreads

Brent Sheppard as Minister

Stephanie Belding as Friendly Nurse

Ryan W. Smith as Joe

William 'Big Sleeps' Stewart as George

Amitai Marmorstein as Young Person on the Bus

Will Reiser as Greg

Christopher De-Schuster as Art Gallery Patron

Adrian Glynn McMorran as Bartender

Karen van Blankenstein as Nurse Scott

Richard C. Burton as Thom the Patient

Susan De West as Bar Girl

Neil Corbett as Hospital Tech

Stephen Colbert as Self (archive footage) (uncredited)

D. C. Douglas as Live Volcano Reporter (voice) (uncredited)

Cameron K. Smith as Chemo Patient (uncredited)

Tom MacNeill as Office Staff (uncredited)