The film is broken into different "chapters" as the narrator reads Edward's journal, which has been passed down from generation to generation. Each time we come to a new chapter, as well as a few other places, there is some rotoscoped and seemingly hand-drawn animation that really brings across the brutality of some parts of the story even more than messily dispatching multiple zombies with blunt weapons and firearms.
My one criticism is that I was amazed at how good a shot everyone was. We had ball ammunition revolvers as well as the newer "Colt" variety, plus shotguns and rifles. Edward was an amazing distance shot with his revolver, getting a head shot nearly every time. Given the period, the unreliable nature of Civil War-era weapons, and the fact that these people were fighting for their lives I expected a few more misses. But that's a minor nit in the grand scheme of things.
In addition to two commentary tracks (one with director John Geddes and actors Adam Seybold and Mark Gibson, the other with Geddes and producers Jesse Thomas Cook and Matt Wiele), there is a great "making of" feature called "Blood Sweat and Tears." It really shows some of the hardships they faced with weather and general conditions where they were shooting, as well as the bond that formed between the cast and crew.
If you like zombie films, I'd definitely encourage you to check out Exit Humanity when it's released on DVD on Tuesday, June 19th.