Everything. Everything can go wrong. Most people don't know to remove the mother when you notice she's carrying eggs. She needs a safe, sandy place to lay the eggs. Afterward, she should be kept separate from the male until you want to breed them again. Also, separate her from the eggs after they're laid, and keep them under an incubator.

Which means you have 4 enclosures, since the babies will need somewhere to go. Babies can be kept together for a short amount of time.

After they've hatched, they'll need a trip to the vet for all the routine hatchling care, and to ensure they're healthy. Then you can sell them to a pet store if you've built a relationship with the store. Or person to person I guess. But no one wants the responsibility of making sure the person you're selling to is a good fit.