The Earth Defense Front (EDF) has a similar name to the real-life group Earth Liberation Front (ELF). The ELF are radical environmentalists who have been involved in arson and other property damage. The FBI considers them to be "eco-terrorists."
The character Evan Abby is inspired, at least in name, by Edward Abbey. Edward Abbey was a writer and environmentalist, whose book "The Monkey Wrench Gang," is said to have inspired the group Earth First! a radical environmental advocacy group.