From that same article (which I had previously read and missed/forgoten) I had found:
The engines and nine other cars remained behind when the rest of the train broke away sometime later. They stopped a quarter of a mile away from their original parking spot in Nantes.
After the Nantes siding there is only single track into town until the yard switches. How does the end of the train get ahead of the front of the train? The TSB pic of the (blue) locomotive make it look upright and still on the track.
The scribes still don't have their story straight.