Eileen Peede, who plays Dr Kessler in this episode Red Meat, played Mrs. Frankle in S5E12, Swap Meat.
This is not the first time Dean has intentionally temporarily died with the specific purpose of visiting the Other Side, getting intel about Sam, and then having someone revive him. He did the same thing in the Season 6 episode "Appointment in Samarra (2010)".
This is the second episode in a row where the story is told out of sequence, flipping between the past and present.
The actor who played as Corbin previously played as Lance Stanley in 8.6 Southern Comfort.