What's supposed to happen at the end? (SPOILERS!)
DANGER!! SPOILERS AHEAD!!
Near the end of the film, after Ben explains to Virginia about the fate of Barbicane and Nicholl, and their own chances of returning to Earth, she tells him that one day the world will know the truth, they embrace, and...suddenly there's a huge flame outside the porthole, with the sound of an explosion -- then, cut to the final scene with J.V., Cartier and Von Metz.
Now, I've watched this film for over forty years, and to this day I can't figure out what exactly is supposed to have happened. Did the remaining section of the Columbiad with Virginia and Ben blow up and kill them? Or are we supposed to assume they return safely to the Earth, since -- as with almost all movies -- when a character makes a statement about something the audience never sees (in this case, Ben's "We might possibly just make it"), we're supposed to take this as assuring us that that is actually what does happen in that unseen development.
Trouble is, no ending is entirely satisfactory from a plot point of view. If they were blown up, it violates the movie principle mentioned in the above paragraph. Besides, after the flame shoots out, it dies away, but the ship still appears intact, as viewed from the shot looking through the porthole (if the ship had exploded, then the porthole and everything else in the shot would have disappeared before the flame).
On the other hand, if the two did make it back to Earth, they could report on what happened, and whether they were completely believed or not, there would be some resolution to the mystery. Yet the final exchange between Jules Verne, Cartier and Von Metz makes it clear that they'll "never be able to prove" what happened, and that the fate of the Columbiad and its passengers will remain unknown for at least a long time to come...not something that would be true if Ben and Virginia made it back home.
So what's supposed to have happened? Were the two lovers killed or not? I don't think there's a definitive answer to this, as the movie is so vague. But any opinions?