Inside of the lens/goggle
If you have snow inside your goggles as the result of a crash or for any other reason, you'll want to take special care not to rub the lens when it's wet.
Here's why: before a goggle lens is assembled the inner lens material is coated with a liquid anti-fog treatment that permanently adheres to the inner lens surface to help prevent fogging. When this anti-fog treatment gets wet, it becomes soft and can become scratched if rubbed.
If this happens again, first clear the snow by patting the goggles on your leg to. Next, with a micro fiber cleaning cloth, blot the inside of the lens to remove any residual moisture. Once the inside of the goggle has completely dried out you can use a micro fiber cleaning cloth to lightly wipe away any smudges.
Outside of the lens/goggle
Snow and ice on the outside lens can also cause problems. Try not to rub the lens when it is wet, instead try patting the goggle on your leg to remove as much of the snow as possible. Once you have done this you can blot the lens with a soft cloth or the included lens bag. Only now should you try to dry/clean the lens with the goggle bag or micro fiber cleaning cloth.
If the lens has ice on it you should try to warm up the goggle before attempting the same process as above.