When doing the autopsy on the goat head, Doc Robbins mentions he has seen the film 11 times and compares the fact that the head was left at the Adams' house porch with the horse scene, as a means to "send a message".
When character acted by Catherine Willows wanted to nail gas company, her boss said she's not Erin Brockovich. Also Marg Helgenberger played a victim of the water pollution in Erin Brockovich.