To be even more specific I would say that it is an embden or male pilgrim goose. It is not unusual for domestics to tag along, but due to their body size i would think that they would not be able to fly with the flock, thus causing constant change and solitary periods.
Well, In the scandinavian countries - and after an animated tv-serie also in other European countries - there is a well known tale of a Kid called Nils Holgersson. In this tale Nils and a domestic goose (Martin) are joining a flock of wild barnacle(?) geese to attend them on their way to the north.
So according to this tale, domestic geese in flocks of wild geese are not that weird as they seems to be