I embarked on an evil biome where my military's first duty was to kill an undead raven that was harassing dwarves but apparently not harming them.
Unfortunately, we apparently could harm them either and they just endlessly tried to wrestle the thing.
Meanwhile, while this was going on, somehow a horse died. I don't even remember embarking with one. Somehow, the horse died in the meeting hall. Shortly thereafter the horse got back up and in seconds flat had killed every single dwarf there.
Despite canceling all orders, disbanding the squad, recreating it and ordering them back to barracks, and anything else I could think of, these idiots stood there trying to wrestle an undead raven when they couldn't harm it and it couldn't harm them. By the time I gave up just waiting for these idiots to starve to death, the raven was just page after page of red text descriptions of everything wrong with it.
This was very early on so my "military" was 4 unarmed dwarves. Meanwhile the only armed dwarves were a woodcutter and two miners who were too busy getting killed in the fort to get involved, and the idiots fighting the raven wouldn't go pick up the weapons, which they would have had to go fight zombies to get anyway.
I guess the lesson is don't bring large domestic animals into these biomes.
Another one: this wasn't my dwarves, though, but the first caravan that visited. I think this is related
to a known bug.
Anyway, I cleverly embarked without an axe and some time before the caravan arrived, a tree grew in the middle of my entrance leaving the trade depot inaccessible. Either that or something else, but in any event, I just built another one because I needed either wood or an axe so it was important I get one of them.
So anyway the dwarf caravan arrived in autumn, and I got the outpost liaison dialogue. However, once that was over, the caravan arrived and just immediately left again. It wasn't until spring that I noticed that they'd not only disassembled their own wagon but dropped everything they had on the ground. Most of the food was rotten by then but in addition to everything else, they left an axe and more picks. I could tell they'd disassembled their wagon because there were wagon logs left behind too. They dumped everything on one square.
The next year they arrived like things were completely normal so it didn't seem to sour relations.