The cape looks a bit jagged, the cape-sky boundary could use a little clean-up. If you're not able to get a smooth curve on it, try adding some undulations instead, in pixel art it's often easier to draw a few small curves than one large curve.
The white 1px "clouds" read like noise rather than clouds. I'd get rid of them, the clouds look like they're receeding well enough without them. Single pixels rarely look good. Single pixels work well for small expected details, but without a lot of context they just don't read well.
You helped me a lot, thank you!