Perhaps I missed something, but what was the significance of that? When the group all gets out to the ranch, Mandy goes for a run and comes across a pool of blood on the dirt road. This was before any of the carnage had taken place, so I don't understand what it was from or was supposed to signify.
If I remember correctly, it was from the sick cows that Garth had to shoot. I think it was just supposed to be ominous, foreshadowing what's to come...
The blood couldn't have come from the cows. Those cows had been rotting in that pit for quite some time when she fell into it. The blood was fresh. It made no sense. Correct me if I'm wrong.
Maybe, but why? His parents were already going to be out of town anyway and not at the ranch. It's frustrating that there's really no apparent explanation for it. I listened to the audio commentary on the DVD hoping Jonathan Levine would say something about it— like maybe that it connected to some other scene that ended up being cut or something— but he didn't.
I figured it was just a way to get the audience into the movie. Mandy doesn't even mention the blood when she gets to the swimming hole. It was completely forgotten about once the scene was over. As the movie went on, I actually thought it was the car's alternator fluid leaking (alternator fluid is red) when I first saw it there. Like maybe something had been done to the SUV and it had leaked when they stopped to leave Chloe's car at the bridge. If it had been blood, then something would have come of it, I kept thinking. Then I expected a "The car won't start! Someone cut the alternator line!" but we had none of that. So, I basically have no answers for you. I am just as confused about it as you are.
I've got two good posts in me and I just wrote my third...