Scott Wilson (Chaplain Farley) has appeared in two other true crime inspired movies with scenes of capital punishment: In Cold Blood (1967) and Monster (2003). And he has appeared not only in "Dead Man Walking" but also in The Walking Dead (2010).
One of the victims' surnames is Delacroix. Coincidentally, this name also turns up in another drama about the death penalty, The Green Mile (1999), but there it was the name of the death row inmate played by Michael Jeter.
The trivia items below may give away important plot points.
In reality, Elmo Patrick Sonnier and Robert Lee Willie, both inmates on whom Sean Penn's character Matthew Poncelet is based on, were executed by the electric chair in Louisiana in 1984; by 1993, Louisiana switched that penalty to lethal injection as the most humane way to execute. Both Tim Robbins and Helen Prejean opted to use lethal injection in the film instead of the electric chair because, according to Prejean's interview, "We don't want to give people the moral (of the most humane death) out whereby people could say 'Oh well, we used to do electrocution but that's too barbaric so now we are humane and inject them'."
Because Peter Sarsgaard and Missy Yager's brutal rape scene was filmed in the mud, every time they did a new take they had to get up, get showered, get dressed, put new makeup on and do it again. It took all night to film.