I was up betimes in the morning...
Watson rose early.

"Students of criminology will remember the analogous incidents in Grodno, in Little Russia, in the year '66, and of course there are the Anderson murders in North Carolina, but this case possesses some features which are entirely its own.…"
Holmes is mistaken--Grodno is in Lithuania, not in Little Russia (the Ukraine). Neither of these cases is real. Again, Conan Doyle creates the feeling of verisimilitude by studding his narrative thickly with names and dates.

	This poster for the 1939 Hound of the Baskervilles represents the hound only as a series of monstrous footprints, rather than trying to show its glowing face

...and I saw at once from the reverential way in which Lestrade gazed at my companion that he had learned a good deal since the days when they had first worked together. I could well remember the scorn which the theories of the reasoner used then to excite in the practical man.
Lestrade's change of attitude towards Holmes's method is usually ignored in movies and pastiches of Holmes and Watson stories. There, he is forever doubting, and yet quite willing to take credit when the mystery is solved.

Fire burst from its open mouth, its eyes glowed with a smouldering glare, its muzzle and hackles and dewlap were outlined in flickering flame.
Now Holmes has an answer to his question from chapter VII: how did Selden know, despite the darkness, that the hound was on his trail? Answer: he saw the phosphorescence.