That goose is pretty cool! Canada geese do come in a leucistic form, they can be either faded to brown, or all white. They can also be piebald, with patches of white. The all white head and neck could be a strange manifestation of either form. Or it could be a cross, as you suggested, though I would expect more in the clutch to look odd if that were the case.
I am not finding anything similar on Birds of North America, whatbird.com, so the duck has me stumped.