The only two others that I can think of are the occasional random rings hidden in the cook pots, but those are scattered all over Enroth, so I probably shouldn't count that for New Sorpigal.
Also, let's not forget that on the island where Gharik's Forge is --- that cook pot nearby, if you click it, brings several goblins to the location! (Similarly, in Rockham, there's a well that, if you drink from it, brings a few Fire Archers to town.)
Not quite related, but the first time you cross the bridge to return to town from the Abandoned Temple causes a few goblins to appear on the bridge. Thus, if my party is very wounded when leaving that dungeon, I'll bypass the bridge by going over to the edge of the stream, and jumping over. If you do it right, you can clear it without ending up IN the stream.
One of my favorite Easter Eggs, for some reason, is that torch in the sewers of Free Haven. If you click on the darkened torch, it illuminates. Apparently NWC had had some plans for it, because the description when you hover the mouse over it is capitalized, but I guess they, for whatever reason, decided to scrap their original plans, but still wanted to do SOMETHING with it.