At the end of the episode, Death greets Dean with bacon dogs and beer in Bobby's kitchen and is wearing the 'ring' he came back to get from Dean, but only for the first couple of seconds. When Death is offering Dean a bacon dog the ring is no longer on his finger. Then Dean pulls the ring out of his pocket and tells Death that he flunked the test.
In "Frontierland" when Castiel needs to heal himself by touching Bobby's soul he makes a point of saying he has to be very careful doing so or Bobby might explode. So it seems strange that both Michael & Lucifer are able to violently abuse Sam's soul in the cage without any such explosive consequences.
A few shows ago Sam reveals to Dean and Castiel that he "doesn't FEEL anything, doesn't sleep, and isn't scared of anything anymore". So, if he can't feel and isn't scared of anything, he shouldn't be FEELING so SCARED of getting his soul back in this one.
When Dean is reaping the robber in the convenience store, various President's Choice products can be seen on the shelf. President's Choice products are not available in independent convenience stores. They can only be purchased from companies under the Loblaw's banner, which operates solely in Canada. The packaging also contains both English and French text, again a requirement for products sold in Canada.
The money in the envelope that Dean pays the doctor with is white instead of green, obviously fake.