Hi LJ,
I loved the graphics! It really looks like a mobile game, and surprisingly I could find most of the correct answers:)
While starting, I missed that star too. I think if START button doesn't appear before the player sees the instructions, you might not need to add a glowing animation, or you can remove the snow on it, and change the color a bit to make it more distinctive.
I would use some music while starting, and cartoon sound effects for the answers. Orangefreesounds has a really nice sound effects collection and background music, you might want to have a look there.
I like the getting extra stars from the forest.
One more thing, if questions are shuffled, it can bring more excitement. By the way, bonus points, at the end, is an element which I will definitely use in my projects more often then. Thank you for the inspiration.