Creation takes time. Time is limited.

“Though ‘Ambrosia’ actually refers to the whole island, its lack of human life results in this name being applied to its dungeons as a whole.” – Key to the Black Gate, the Ultima 7...

Some of the rune stones produced by Runekeeper in Ultima Underworld 2 are marked as Kal stones, but actually function as Corp stones.

It is actually possible to cause Killorn Keep, a floating fortress the Avatar visits in Ultima Underworld 2, to fall from the sky and crash into the desert below.