Green produced and directed documentaries for National Geographic and David Wolper, including The Hellstrom Chronicle, for which he was accorded the Oscar and the BAFTA in 1972, and The Secret Life of Plants in 1979.
Among his screenwriting credits are the films The Wild Bunch, Sorcerer, The Brink's Job, Solarbabies, Eraser, The Hi-Lo Country and RoboCop 2.
More recently, he was a Creative Consultant for the Chris Carter science fiction TV series Millennium, where he co-wrote the episode "Paper Dove" with Ted Mann.
He is also notable for allowing a millipede to crawl over his face in the tunnel scene of Willy Wonka & the Chocolate Factory.
In 2008, Green was the Head Writer/Showrunner of the television pilot Bunker Hill, starring Donnie Wahlberg and Bridget Moynahan and directed by Jon Avnet.