List of things that seemed unusual to Black Beauty when he woke in the night.

Assuming you are referring to Chapter Sixteen, Beauty was uncomfortable when he awoke. The air was thick, and Ginger was coughing. Beauty also heard strange noises.... crackling and snapping..... noises that frightened him.

I cannot say how long I had slept, nor what time in the night it was, but I woke up very uncomfortable, though I hardly knew why. I got up; the air seemed all thick and choking. I heard Ginger coughing and one of the other horses seemed very restless; it was quite dark, and I could see nothing, but the stable seemed full of smoke, and I hardly knew how to breathe.

The trapdoor had been left open, and I thought that was the place it came through. I listened, and heard a soft rushing sort of noise and a low crackling and snapping. I did not know what it was, but there was something in the sound so strange that it made me tremble all over. The other horses were all awake; some were pulling at their halters, others stamping.