When Dr. Buchanan (John Hurt) runs across the three slaughtered sheep in the woods at the beginning, closer inspection reveals that not only are they still alive, but asleep and breathing, and the supposed entrails are actually placed strategically on the sheep and not coming out from inside them.
When Dr. Buchanan meets up with Lord Byron in the grounds at his estate, quite visible in the background is a car driving across a bridge. Buchanan wasn't the only person, it seems, to own a car in 1817.