I didn't give this story much credibility when I first heard about ita few weeks ago. After all, how can you simply 'lose' a train on a stretch of railway linking A to B? Surely any blocked up tunnel would be excavated, the train found and the route re-opened?
However, it appears Walbrzych (apologies if I've spelt it wrong!) is in an area that contains many miles of tunnels and bunkers that were excavated by the Germans between 1942 and 45 - for unknown purposes, although possibly it was intended to move war production factories here to be safe from Allied bombing. It is quite likely that at least some of these complexes were served by spurs leading off the main lines.
It would then be entirely possible route the train on to such a branch, run it into the tunnel and blow in the entrance behind it.
However, there would presumably be some surviving witnesses, but in the turmoil of the last months of the war they would become widely scattered and have many more immidiate issues to deal with!
As mentioned above though, the fact remains that it would be relatively easy to ascertain the route of old branches and sidings, even after the rails had been removed, by the surviving earthworks and the old tunnel entrances themselves would be obvious, even if blown in. A fascinating story and I can't wait to hear the next development.
I may, unknowingly have even passed near the site back in 1990 on the footplate of a Polish Pt47 2-8-2 steam loco as I cab rode various locos around this area in the last days of polish steam. Colin.