The cover illustration portrays Dumbledore with a normal-looking
right hand, but the text makes it clear that it is Dumbledore's right
hand and arm (p. 58) that are blackened and shriveled (p. 48), and that
are still in such condition at the precise moment depicted by the cover
illustration (p. 567). Thanks, Brent!
In the American edition, when Dumbledore and Harry enter
Horace Slughorn's house, something "darkly red and glutinous was
spattered over the wallpaper." Later, when asked what kind of blood it
was, Slughorn explains, "On the walls? Dragon... My last bottle, and
prices are sky-high at the moment." (p. 65) However, in book 5 (OotP),
when Hagrid finally returns in chapter 20, he is nursing his bloodied
face with a green-tinged steak of dragon meat. "He picked up the steak
and slapped it over the left side of his face. Greenish blood trickled
down into his beard as he gave a soft moan of satisfaction." (p. 422) Thanks, Stephanie!
In the American Edition, page 188, Slughorn says, "One tiny
bottle of Felix Felicis enough for twelve hours' luck. From dusk til'
dawn, you will be lucky in everything you attempt."
But then on page 476, Harry says, "I don't reckon I'll need all of it, not twenty-four hours' worth..." Thanks, Sandra and Esther!
On page 176 of HBP, UK edition, it states "Malfoy looked rather as he had done the time Hermione
had punched him in the face." However, on page 216 of the UK POA, Hermione "...had slapped Malfoy around the face with all the strength
she could muster." Thanks, Mia305!