What it says on the tin. (Including Follow-ups to: Maybe one of these days you can let the light in, and One Of Those Things, and Mrs and Mr Pond..)

Apparently Supernatural was real, which was presumably why Gabriel was bleeding out onto Richard’s floor. (In which the actors of Supernatural find that reality is stranger and more disturbing than they previously believed, even counting Misha, and an injured archangel discovers that his universe is the subject of a TV show.)