John Lithgow as John Mathewson

Christopher Collet as Paul Stephens

Cynthia Nixon as Jenny Anderman

Jill Eikenberry as Elizabeth Stephens

John Mahoney as Lt. Col. Conroy

Richard Jenkins as Radiation Controls Officer

Sully Boyar as Night Guard

Timothy Carhart as Relief Guard

Gregg Edelman as Science Teacher

JD Cullum as Eccles (as John David Cullum)

Abraham Unger as Roland (as Abe Unger)

Robert Sean Leonard as Max

Fred Melamed as Howard

Ned Eisenberg as C-4 Guy (uncredited)

Richard Council as Government Aide

Robert Schenkkan as Government Aide

Steve Blum as Laser Efficiency Kid (as Richard Cardona)

Sarah Burke as Jenny's Parent

Warren Manzi as Day Attendant

Paul Austin as General

Adrian Sparks as Scientist

Curt Dempster as Scientist

Bran Ferren as Lab Assistant

David Quinn as Tennis

Geoffrey Nauffts as Craig

Katherine Hiler as Emma

Trey Cummins as Terry

Steve Borton as Local FBI

Harlan Cary Poe as Local FBI

Ned Schmidtke as Jenny's Parent

Allen DeCheser as Jenny's Brother

Artie DeCheser as Jenny's Brother

Fred G. Smith as Conroy's Lieutenant

Manny Jacobs as Moore

Charles Fields as Price (as Charlie Fields)

Eric Hsiao as Saito

Heather Rose Dominic as Flirting Kid

Bruce Smolanoff as Flirting Kid

John Doumanian as Cabbie

Tom Tarpey as Injection Doctor

Roger Caine as FBI (as Alec Massey)

Edward D. Murphy as FBI

Joan Harris as Barbara Collins - TV Reporter

Ken Chapin as Command

Peter McRobbie as Electronics

Warren Keith as Computer

Bruce Jarchow as Interrogator

Stephen Markle as Interrogator

Al Cerullo as Helicopter Pilot

Michael Telesco as Day Security Receptionist

Richard Caselnova as SWAT

Frank Ferrara Sr. as SWAT

Jimmie Ray Weeks as SWAT

Dan Butler as SWAT

Steve Zettler as SWAT

Debbie Gibson as Background (uncredited)