Canadian visiting family working in China

I am a Canadian citizen working in South Korea as a teacher and when I am finished in November I would like to visit my sister who is currently working in Beijing before taking the transiberian train to Russia on my way home. Is there anyway to get a week long visiting visa without having to add time to my foreigner card in Korea? Will having my tickets booked to leave China via the train help? Would it be possible for me to get a visa if I applied from another country, such as Vietnam or Japan after I leave Korea?