Sure wouldn't want to piss off the green box he looks big and angry . On that same pic I see that the rendered " floor" is blueish whilest de background( which is probably comped in is yellowish I would match the colors a bit more. ( keep in mind that the sun gives a hard direct yellowish light and depending on what the weather is, the atmosphere tends to give a blueish indirect light or a greyish one ( if the weather is crappy like here in the Netherlands) with soft shadows. I don't know if the images are actual shots from your movie, but if it is, try to keep te characters on the same side of the screen on image 2 the yellow cardbox character is on the left while on the 3rd image it is on the right. Looks promising though I agree about the colors of snow, but with the images 2 and 3, the yellow box is on the left because it's a shot from behind, then a shot from the front would make him be on the right. So that's fine the way it is.