These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Everyone Is Jesus in Purgatory: The conversation in the limo at the end of the movie could easily be portrayed as symbolically taking place between the Father and the Son just after the crucifixion. Except that the Father convinces the Son (Grace) that all those wretched sinners aren't worth saving and shouldn't be forgiven.
In which case the ending would be a commentary on just how special the real Jesus' forgiveness is supposed to be.
Fridge Horror: Grace sparing the dog at first seems like a rather kind gesture, until you realize that the dog is now alone in the middle of nowhere without anybody to care for or feed it, and will probably go the way of the townsfolk fairly soon.
Double dose: thanks to the massacre, there's actually quite a bit of food available to the dog. So, he might survive... but only by going feral.
Moral Event Horizon: Everyone gets their moment, YMMV if Grace crossed it at the end massacring the entire village