I think you really could combine those first two.

Our train hit a snowdrift a thousand miles from Bisalu Port leaving us temporarily stranded in the middle of nowhere with nothing but miles of ice all around.

A good setting for a murder-mystery, but since no one got murdered, we whiled away the time telling ghost stories.

This is what went “clunk” to me -- but since no one got murdered.

Consider – but, since no one felt like killing a fellow passenger, we whiled away…..

Just me, a newly-wed couple on their way to Lake Opaloho, and four wide-eyed children returning from holiday with their sour-faced guardian. I endured three or four tales about ghost ships and ghostly-train conductors,

This sentence is another fragment – a list. The first thing that bothered me there was the “Just me, a newly--wed couple – I initially thought that the me was going to be expounded on by the “a newly-wed” but the couple precluded that. It was an annoying little nit, but one right there in the opening.

There in the dining car were a newly-wed couple on their way to Lake Opaloho, four wide-eyed children returning from holiday with their sour-faced guardian and me. I endured three or four tales about ghost ships and ghostly-train conductors,

It’s just my opinion, of course, but I think making it another complete sentence and moving the “me” closer to the “I endured” makes for a stronger segue.

Unfortunately I used dining car so it would then be necessary to give a touch more information rather than repeating what was already given. You could tell something interesting – was there a candle on the table where there faces were pressed close? Actually, that many people in a dining car, around a table presumably – how do you get “pressed close” ????

I think it is the presence of so many sentence fragments that was my main concern here.

But I liked this opening. Good work with the concept.

Oops! I forgot the last nit.

before the ships came down and the world was still a mysterious place.”
 is confusing. I think you must have meant –

before the ships came down, when the world was still a mysterious place.”

Otherwise I can’t decide whether the world was a mysterious place before the ships (good tease) came down or if the world became a mysterious place after they came down. Even with the “still,” I have that confusion.

I'm a real bear on clarity.