Ah ah, I opened this exactly to see if Supernatural was going to be mentioned. Read it as "(this is) the road (we have traveled) so far (on)", as a way to introduce a recap of the past episodes.

It would be useful to see the whole context, Esther, because there are two possible meanings. 1. The more common expression 'so far' means 'where we have got to in our journey'. So you could say 'So far, we have covered 4 out of 6 topics in our class.' or 'We have covered 4 topics so far.' So if your phrase says something like 'We have covered 20 kilometres on the road so far.' it means where you have got to on the journey along the road. 2 There is a more romantic use of 'so far' as an adjective, meaning far away - in fact so far away it is only a dream for you. It is older style writing. 'The road so far' would be a road that stretches into distance you can hardly imagine.

"The road so far" is used to describe a journey which isn't complete. "The road is so far" would describe how far away a road is.