Warning:
The below hints may make the Ravenloft gameplay less pleasurable.
Read at your own risk. :)
The scroll with the hints as to how to reach the secret chambers is located in the Thief's Den. When you enter the room, go to the right chamber, and then turn right. The section with boxes for picks, probes, and keys. The scroll is on the floor, peeking from behind a basket. Only its tip is visible, when you stand just so.
Before reading any further, try finding the hidden areas using the hints found in the scroll.
Here are the clues on how to access the hidden areas in Ravenloft:
The entrance lies on the floor...
Before sleep, a resolute adventurer should turn off the lights...
A devoted Samurai always goes where Honor dictates...
The Jade Dragon is in the hands of Buddha, but only a true Ninja can walk on air... and remember - if a ninja cannot walk through it, he tries to walk around or above it.
A clever Mage always keeps his Lab warm and well lit...
Glowing red letters will guide a resorceful Mage...
The key can only be found in the horn of a Unicorn...
On the way to the Quarters Display, you reach to the door knob, and...
There is a chest standing alone, almost without purpose... Why is is there?
Maybe to draw the attention to the general area... search, search, find!
The Secret Storage can be reached from the Quarters. Go to the bedroom, and click on the tiki-torch which is farthest left from the bed. This tiki torch is actually a teleporter which takes you to the Secret Storage.
The Panic Room can also be reached from the Quarters. In the bedroom, click on any of the 3 carpets around the bed. Each of them will teleport you to the same Panic Room. Teleporting back from the Panic Room will place you in a slightly different section of the Quarters, so you can get a moment to orient yourself before being attacked.
Summoning Chamber can be reached from the Mage's Lab. Go to the magic area (as opposed to the alchemy area) and click on a specific one of the daedric tapestries. The one just oposite the entry will do.
Secret Mage Display can be accessed by clicking on one of the logs placed next to the fireplace in the Mage's Lab. The log closest to the wall is the activator.
In Dojo, click on the Honor kanji plaque. It is located in the far right corner of the dojo, behind the bamboo planter. From the Secret Samurai Stash you can access another small room by clicking on the small dragon statue.
The entrance to the Secret Ninja Shrine can be also found in the Dojo. Go to the Buddha statue, and carefully move the mouse cursor around the state's hands. The statue holds a small button which will teleport you to a platform right on top of the Secret Shrine. It is hard to see, and hard to activate, but true ninja has a lot of patience. :)
Once on the platform, in the distance you will see another platform. You will have to walk towards it seemingly on thin air. Do not worry, there is an invisible bridge connecting the platforms. In the middle of the bridge is an invisible obstacle - you need to jump up on it, and then squeeze on the right past it. From then on, reaching the other platform is easy. Activate the small dragon statue and it will teleport you to the Secret Ninja Shrine. Once in the Shrine, each of the large dragon statues will teleport you to its own small room.
In Library — in the small room with two desks... look at the wall which has two Unicorn tapestries... One of the Unicorn's horn is replaced by activation button... press and presto!
In Quarters — go downstairs all the way to the door leading to the Quarters Display. Look at the door handle. Within it, is the teleportation activator. It will teleport you to the Secret Display Chamber.
In Quarters — go upstairs to the lne chest standing there seemingly without any reason. The tapestry over the chest is a teleportation activator. It will get you to the Hall of Tranquility.