of course their is elrond, a couple brief mentions of gondolin, the elven king of mirkwood not named until the lotr as thranduil.
the necromancer (sauron of course) who they did not know was growing again in power in his fortress of dol guldor in mirkwood before the rebuilding of the dark tower in mordor.
but the elves are entirely too childish and unlike the elves of lotr are very merry folk who laugh and joke and are jolly.
plus their are the authorial interuptions in the book the asides to readers which ultimately came out of tolkien's reading to his children.
later he would call talking down to children a mistake and though it is their in the early drafts of lotr the finished product became much more terrible and adult like.
according to the new history of the hobbit books tolkien had the intent to almost rewrite the entire hobbit and not just the riddles in the dark chapter V, he did some preliminary revised notes but never carries them through. he was also going to rewrite the silmarillion to fit the lord of the rings, he wanted a consistency between all the works parts as he saw all three works as part of the whole.
he never did finish the silmarillion or write the hobbit more in line with the lotr.
and even though they were not published chronologically it was his hope that the silmarillion be read first, the the hobbit and finally the lord of the rings, this is also christopher tolkien's approach to the material.
my favorite parts of the hobbit are the references to norse myth, the philological stuff like the riddles in the dark obviously taken from old english book of riddles. as well as the references to beowulf and the hrolf saga like beorn the were bear or skin changer.