The prison warden and executioner is played by Frank Thompson. Frank was the technical advisor for the lethal injection sequence. He had served as the superintendent for the Oregon State Penitentiary, and he developed the lethal injection system used there. The producers wanted the execution scene to be as accurate as possible, so they took pains to find someone who understood every step of the process and who would be willing to talk about it. He performed the role on the show exactly how he would have performed it in a real life. Thompson is an active advocate for the abolition of the death penalty.
The suit Billy wears to Mexico is inspired by that worn by Cary Grant's character in "North by Northwest (1959)."
Casting amputee actors wasn't an easy task. The producers wanted to be delicate and to show a fair representation of people who have had amputations. The producing team went above and beyond to travel in the actors from across the United States.
The flashbacks to Cooperman-McBride in Season 2 are meant to show how much warmer the law firm was before Billy left, a more intimate and snazzy place. In Season 1, the law firm was a very cold and dark place.
The set used as the church was the Pasadena-area childhood home of musical artist Jackson Browne. A picture of the church can also be found on the cover of his album "For Everyman."