If a dwarf sees you eating a dwarf corpse, he grows enraged and gains to-hit and damage bonuses. This may also extend to other races seeing you eat their fellow kin, though orcs might just laugh instead.

You can tame (or at least pacify) hostile dwarves by throwing potions of booze at them, which they catch.

Minetown shopkeepers should be gnomes, and the priest and Watch should be dwarves, either by creating new racial variants of those monsters or via a monster race implementation. It doesn’t make any sense that everything in the town is run by humans.

Elves sometimes carry lembas wafers, dwarves carry cram rations, and orcs carry tripe rations.

Dwarves don’t go within two spaces of a tree if they can help it. (This is an Order of the Stick reference.)

Dwarves don’t tunnel within Minetown limits (they can dig up the outer areas of the level just fine).

Ankh-Morpork levels in the Tourist quest should be populated with some peaceful humans, dwarves and trolls. However, the levels should also then avoid having lots of narrow corridors so it’s not incredibly frustrating to traverse them. (Or implement peaceful displacement).