Described in a magazine back in the 1970s was Sunday services departing from Bristol were being diverted through specially-cleared carriage sidings due to work on the main tracks alongside. However, one apparently well-loaded service was inadvertently further routed along the track with the washer unit, it operated the starting treadles, it was a hot summer day, it was Mk 1 stock with all the toplights open ..........
Meanwhile the Manchester to Glasgow/Edinburgh services of that same time were divided at Carstairs, the back always reversed to Edinburgh and the front went forward to Glasgow - except one Monday when the stock had somehow got reverse-marshalled after weekend diversions, so the plan was to do a bit of extra shunting at Carstairs to restore things. Despite extra announcements at some (not all) stations, and a ticket check, done far too early back in Lancashire, about 30 passengers for Glasgow suddenly found themselves setting off backwards from Carstairs for Edinburgh, they didn't think anything of this initially as there had already been one extra reverse shunt as the portions were divided, but it just kept going. I wouldn't be surprised if as many went off in the Glasgow portion by mistake as well.