The only problem is I (as DM) can't point out whether any of these are significant. Whilst the note's obviously important, and the players have a copy, the Rivenroars and the funny portal-place might be totally meaningless, and I don't know whether to stress it or leave it as interesting backround. Unless I'm told in advance that the Rivenroars are going to be important, I can't really make a big deal of them!
Which is just about the biggest problem there is. Without advance info we don't know what to cut, what to replace, and so on. We're forced to run the adventure verbatim, losing a lot of what makes pen and paper games enjoyable - the way to customise a adventure to your group's taste.