Harry Potter and the Sorcerer's Stone
"And now there were only three people left to be sorted. 'Thomas, Dean,' a Black boy even taller than Ron, joined Harry at the Gryffindor table."
Rowling should have switched the order of those two sentences in order for the whole instance to be logical. I think she meant that Dean Thomas had already been sorted as he ambled over to the Gryffindors and she noted the number of students left.
I have the British and American versions. In the British version, there are only three people to go. But it was changed entirely for Americans as evidenced by the title changed. Dean Thomas is the one not mentioned in the British version. It also says nothing as to his race. But Dean Thomas is definitely a first year. Basically what we have here is overly politically correct publishers trying to fix a mistake, but they didn't do it properly.
I have been working on a comparison of the British and American texts. I've only got it about half done yet, but you can see the difference between the two versions of the sorting scene if you scroll down to chapter six: http://helenajole.freeservers.com/home/Harry.html