Bug: I've only encountered it once and it was at the end of the round, so it didn't bother me. Just wanted to let you know.
Hover: I think it would be great to see the bonus-combinations, when you hover with the mouse over the cards (on the field and in hand) to see what kind of tiles they require to give extra points. (e.g. Hovering over a crocodile would show that you need a lake and a river to get the extra points.)
A few ideas/suggestions:
The wall-card is very strong atm. Also maybe it could be replaced with a grass card. It feels weird that it gives so many points to everything, when it's just a wall which would make people and animals be cramped in.
If you want more strategic depth maybe you could give some infrastructure cards the ability to play the second card in hand.