railroad into the mists

[DustBunny]

Another was in Dungeon Magazine #44, 'Train of Events' and it is similiar to the vanishing train secanrio.

Basically (underground, mostly secret and very primitive) dwarven steam trains as disappearing without a trace in a section of tunnels, and the PC's are sent to find out what happened and to retrieve the miners payroll - and the crew if possible.

Mists are not responsible though, more hijackings.
Interestingly, another adventure in this issue was "The Hand of Al-Djamal" which was loosely about a mummy curse in a museum.

Also it does not have to be a train as we think.
Sure you have rails and cars being pulled along, but the actual motive source could be a golem on a treadmill, skeletons (hidden of course) turning handles or even mudane sails (a rail boat?).