He acted in movies and television from an early age. Turning to writing in the 2000s, he co-wrote and co-starred in Manic. As of 2007, Bacall has sold a number of scripts to major studios, including Psycho Funky Chimp and In Search of Captain Zero.
In June 2007, New Line announced that Bacall will be writing a feature adaptation of the documentary The King of Kong. He co-wrote the adaptation of the Canadian graphic novel series Scott Pilgrim, Scott Pilgrim vs. the World, with its director, Edgar Wright.
He is also writing an upcoming Tropic Thunder spin-off, with Tom Cruise in the lead reprising his role as Les Grossman.