True stories that seem impossible...

There was a Pennsylvania boxcar that needed repair, and so was shoved on to a storage siding to await repair sometime in 1932.

 When the Pennsylvania RR went bankrupt and was merged to form the PennCentral in the mid sixties, they started cleaning out sidings and scrapping things all over the system...the old car was drug out and inside it they found two brand new 1933 Packards.

https://www.facebook.com/groups/Fordmodelt/permalink/10159277654945548/

Similarly:
there was a thread in 2006 on the Monon Railroad Historical-Technical Society discussion website that had this story reported there: The Milwaukee Road was pulling out their southern Indiana line in the 1961-1962 time period.

Between Bedford and Jasonville, they came to an abandoned siding only to discover that is wasn't quite abandoned, it had a box car still sitting on it! The box car was opened and was filled with World War II Jeeps! All brand new!!

http://www.rypn.org/forums/viewtopic.php?f=1&t=19979&start=0

Also:
Another version of the story is about a PRR spur somewhere in Pennsylvania and a carload of 1942 Chevy's. Heard from a PRR track supervisor back around 1959.

Also:
Back in 1986 Conrail tore up the former Lehigh & Hudson River Railway from just south of Sparta Jct. to Belvidere, NJ. The siding at Allamuchy was in use until the end bringing in boxcars of feed.

Well when the scrap train got to Allamuchy there was still a 50 foot Penn Central boxcar on the siding. They pulled up all of the track except that under the boxcar.

In other words they left the boxcar stranded there. So for the next few years the Allamuchy freight house and the boxcar sat there forgotten.

Also:
around 2001 the Soo Line tracks through Holdingford Minnesota were pulled up. An old empty boxcar that had been used by MoW was left there and is now part of the rail-trail rest area.

The scrappers had bought the rail but not the car and it wasn't worth the trouble to try to sell it or else the rr just forgot it was there. Friction bearings so it wasn't worth the rr moving in any case.

Also:

The story of the Church Hill Tunnel in Richmond is one that was documented in the book "Scalded to Death by the Steam"

The Church Hill Tunnel was once the C&O's main route through Richmond but was abandoned a/c unstable soil. The C&O built a new route alongside the James River through downtown Richmond. As traffic increased years later, there was no room for expansion of that rail line so the C&O decided to re-open the tunnel in 1925 and use it as a bypass during times of heavy traffic.

The tunnel cave in caught a work train working on the reopening and not a regular train. Since the equipment was old, and the dirt in the hill unstable, the railroad left it in place. And although there are a couple of laborers whose bodies were never recovered, the engineer's body eventually was, by digging down through the top of the hill until the tunnel was broached! The fireman, although escaping by crawling out under the flat cars, was badly scalded and died of his injuries shortly thereafter.

It seems that the basic rationale for leaving the locomotive was that it was not worth much, and recovery would have been very hazardous. The hazard also argued against going in and digging through the cave-in to look for bodies. So they sealed it up and considered it to be somewhat of a tomb. The tunnel was through clay that proved to be quite unstable, with subsidence showing evidence at the surface above. The tunnel lining was deemed to be structurally inadequate.

 While it was not a valuable locomotive at the time, it would certainly be an interesting artifact today. It would not be the most difficult lost locomotive to recover.

The locomotive involved was a 4-4-0 American Standard type, class A-5. C&O #231 was originally built for the Chicago, Cincinnati & Louisville (as its #54) by Baldwin in 1903

https://en.wikipedia.org/wiki/Church_Hill_Tunnel

Church Hill Tunnel is an old Chesapeake and Ohio Railway (C&O) tunnel, built in the early 1870s, which extends approximately 4,000 feet under the Church Hill section of Richmond, Virginia. In 1925, the tunnel collapsed on a work train, killing four and trapping a steam locomotive and some flat cars. Rescue efforts only resulted in further collapse, and the tunnel was eventually sealed for safety reasons.

After completion of the riverfront viaduct in 1901, the Church Hill Tunnel fell into disuse for over 20 years. Then in 1925, to add capacity, the railroad began efforts to restore it to usable condition.

 On October 2, while repairs were under way, a work train was trapped by a collapse near the western end. Two workmen crawled under flat cars and escaped out the eastern end of the tunnel, as did the fireman Benjamin F. Mosby (who died hours later because of the burns caused by the ruptured boiler), but the engineer Thomas Joseph Mason was killed and two other workers were unaccounted for.

Left inside was the work train complete with a 4-4-0 steam locomotive (engine #231) and 10 flat cars.

if that seems fantastic, read about the steamboat recovered from the banks of the Mississippi http://justacarguy.blogspot.com/2016/02/this-exceptional-steamboat-deserves.html