I had a couple of friends who did get their Entry Visa in Beijing and it is same day service. aas long as you have all the required supporting documents, there is really no reason for Canadian embassy to reject you. Though I personally prefer to play safe but if you have to get your visa in China, here is my two cents.
* d1 ]/ ^7 c) l3 F6 h& F
7 p* U- y5 s B1. Go get your visa exteneded first thing after you landed. so you have more time to react if anything goes wrong.
5 E Q( ^: |: P3 [2 N4 U5 l2. Have a friend over here you can contact, in case you missed some support documents, then you can call your friend to get it and fax it to the embassy.