Continuity mistake: Towards the end, right after Mia crawls through the tunnel and into the shed, she backs up against some shelves. There is a lot of blood on her face and her hair is hanging over her face. The shot changes to a close-up and her face now has much less blood on it and the hair that was hanging in her face is gone.
Trivia: In addition to many other nods to the original film, this remake also has several audio clips taken directly from the original film. One of the more noticeable instances of this is when Mia is first possessed, right after the door is thrown open by the force outside of the cabin (right before she vomits blood onto Olivia and is thrown into the basement). The lines "You will die, like the others before you! One by one we will take you!" can be heard in the background as Mia screams. This is taken directly from the original film, from the scene where Cheryl was possessed. In addition, when the main characters first arrive at the cabin, a low, demonic voice moaning "Join us" can be heard in the background. This is another audio clip taken from the original film.