I'm not sure if this is the right place to post this, but I didn't find anything when I did a search.
Looking through the Bestiary 3, I noticed that the Peri, on page 201, is missing a speed entry.
Amalgamite has both the Rare and Uncommon traits listed in its stat block. The "Creatures by Level" table at the end of the book has them listed as Rare, so that's probably what's intended.