1. Jean Valjean acquired some silver from the bishop. 2. It was established that M. Thenardier looted the deceased soldiers at the battle of Waterloo. 3. The existence of Fantine and possibly Cosette had been established? 4. Perhaps Valjean had become the mayor of some town after using what was formerly the bishop's silver to become an honest man?
Note that Javert, who is the other major character besides Valjean has yet to put in an appearance, despite showing up in perhaps the first 10 minutes of the musical. M. Thenardier is, at best, a minor player in the musical, and prior to his introduction, we get ~50 pages on the history of the Battle of Waterloo.
The Princess Bride gently mocks the genre by advertising itself as "abridged". I can't help but feel it's justified.