I love this 'Coin'. It is, as you say a fake but I think it's quite a good attempt. Only problem is Wilhelm was not at the helm as it were in 1878! I think they were produced as a bit of Teutonic humour, we all know what a laugh these Germans can be!! Here is a site describing these 'coins'. It's in German but Google translates it quite well. Wertanfrage: Münze Wilhelm II Deu.Kaiser, 50 Mark, 1878 ? Numismatikforum
Hope this helps. PS I'm not anti-German or anything like that. It's an ex-wife thing!!!