Hall of Harsh Reflections Queries

[Dichotomy]

I'm hoping that I can get some assistance with this adventure. I have searched the archives, and I know there is a LOT of helpful information, errata, explanations, etc. However, it is hard to find specific information that is pertinent. I was hoping that I might be able to convince you fine folk to help me collect some of it here.

Specifically, I know that DMs have come up with unofficial errata (e.g. the DC on the mind blast being 20 rather than 23). I also know that Jason Bulmahn posted at least once that the "shaded planks" in D7 are meant to be the three surrounding the middle pillar (I certainly couldn't tell).

So, if you are willing, please share what you can.

Oh, and I've read the room description several times, but I can't seem to get my head around D9.

[TerraNova]

D9 is basicly the control room for the pit in D8. To get there in the first place, the party must have someone dive into that pool, and then handle the mechanism underwater.

I think it is some kind of failsafe - in case intruders overrun the warehouse level, they hope that they wouldn't dive into octopus-infestdd waters.