@missmushy Cute! I would make the top of the umbrella a little rounder and the far side of the jacket (santa's left side) a bit shorter. Also, it looks a little like the boots are on the ground because they are otouching the building below. Maybe just move that building so his feet look airborne. Love the way you did the reflection on the belt and the "hairyness" of the beard, etc.
On the lower one, those wheels and the cart are off. I always have trouble with perspective but, I think there are others who could give you some better tips on that. You might like to look at the video on perspective drawing and use some box-like frames to help you put things right. I never would have thought of a giant beetle pulling a chariot with Santa in it :-) Very original and creative idea I've always thought it would be fun to give a picture like this to a kid and have them make up a story about it or, even an adult writer :-)