I had that one once where I was wandering near a Giant and his two Mammoths, when suddenly one of the Mammoths appeared 70 or 80 feet staight up in the air, hanging there like a cartoon for a brief moment before falling straight back to earth and keeling over dead. The Giant and other Mammoth didn't bat an eyelid, which I thought was strange, but it made me smile.

Then recently I had a quest action to go and see someone in her shop. When I got there and went inside, she was right by the door about to leave, and exited before I could say anything, so I followed her out. When I got outside she wasn't there. I turned back to the door, and you know how when you get close to a location marker you can see it through walls and floors and stuff? Well I saw this NPCs location marker dropping through the floor. After half a second or so of falling I heard her say, "WAUGH!", as she landed, and then proceeded to wander about underneath the map! Would've been a perfect moment for her to say, "Wow, I've never seen anything like *this* before!". I was worried it was going to mean a broken quest, but after entering and leaving the shop again she was back on solid ground.