From the Summit to the Ice Palace, the Jack Frosts and the Mistinus (sp) fight amongst themselves when you encounter them. I believe the reason for this is the Jack Frosts' cone of cold. The Mistinus don't seem to have a resistance to it so it hurts them when Jacks fire their spells off at the players. In return you have a Mistinu that's very angry at the Jack. My suggestion is take out the Mistinus (not sure why they're even there, understand though elements play a big part of the ravenloft setting, but maybe an air map for the air folk and keep the cold folk on the cold map) or give them resistance to cold above the weather damage.
The Golems in the ice palace, not sure about this one, but we had someone with a +2 sword and they couldn't damage them. Something we're missing about these guys?
The areas designed for mid-levels (or rather the creatures in certain areas) are not giving xp to the mid levels. So there is a gap between high level creatures and low level creatures. One of my characters is level 10 and I can't find anything that's worth a damn xp wise (obviously not my motivation for being here but something I've noted) that's intended for his level. I instead visit the areas meant for 15+ characters when PVM'ing. And come to mention it, all his xp from level 8 to level 10 was rp/dm xp. So areas in the Spider Cave, Werewolf Den, Sullen Forest, Abandoned Farmhouse, and various road encounters should have their xp gain reviewed for their difficulty. Sensitive suggestion, I know, but low level and post 15 characters seem to have the right mix of difficulty and award setting - even if high level areas are currently scarce.
Maybe on purpose, and certainly funny as hell, but every monster enjoys attacking the local wildlife. Can't tell you how many times I've seen players running from werewolves to see the creature instead make a sharp right and chase after a poor little mink.