Revealing mistake: When Danielle's perfectly aimed apple causes Henry to fall off the horse, his scabbard (at Henry's left) bends and flops around despite the fact that Henry's sword is supposedly in it, as seen in the following shots. (00:14:30)
Continuity mistake: When Auguste falls off his horse, the ground leading to the gate is blanketed in long pronounced shadows of tree trunks, but when young Danielle runs to him the only shadows are of treetops (branches and leaves). (00:09:55)
Continuity mistake: When Paulette is dressing young Danielle, before her father's arrival with the new stepmother, just before Louise says, "She must be lovely," she passes the window with items on the windowsill. When Daniel runs to that window the items change. (00:04:30)
Continuity mistake: After Danielle leaves the ball, when Leonardo places Danielle's glass slipper on the stone ledge near Henry, its position changes between shots.
Other mistake: When Queen Marie tells Henry he was born to privilege and it comes with specific obligations, Henry says, "But marriage to a complete stranger never made anyone in this room very happy." Then, King Francis demands, "You will marry Gabriella by the next full moon." The problem is Princess Gabriella of Spain is named Princess Gertrude in the credits. (00:34:05 - 01:57:15)
Answer: They would have become indentured servants - basically their debt be bought by someone in the Americas and they would be forced to work for the buyer until the debt had been worked off.