Hi, I like the ending animation where the duck crashes into the planet.
Biggest improvement would be a better player controller. At the moment you have no acceleration time, so you instantly move at max speed when pressing a button. This makes it very difficult to microadjust your position so its easy to tap a key and fly off the platform. Easiest way to implement this is to add your movement direction to your velocity, and then if you velocity is above the max speed, set your velocity to the max speed.
I'm not sure whether it would fit but another potential addition would be "Coyote time", where if you try to jump just after leaving a platform you still are able to jump. This makes it a bit more forgiving, as especially without any acceleration time I regularly walked off before pressing jump. But this problem might be fixed by the previous suggestion anyway.