I'm sure you didn't do anything really wrong. I'm sorry, but I don't know enough about crops yet to be able to give you any advice about that so do post on the emergency/illness forum about the hard crops.
If they were outside, they should have been picking up grit and they may have quite a bit in their crop. If you were giving them treats or anything besides crumbles without grit that can be bad. They have to have the grit to grind up anything besides crumbles but they should get that outside from the ground. If they were eating other stuff inside the brooder without regular access to grit, they may have an issue there.
Don't be too scared...they're acting normal, they're certainly warm enough and you're taking good care of them!
If they were outside, they should have been picking up grit and they may have quite a bit in their crop. If you were giving them treats or anything besides crumbles without grit that can be bad. They have to have the grit to grind up anything besides crumbles but they should get that outside from the ground. If they were eating other stuff inside the brooder without regular access to grit, they may have an issue there.
Don't be too scared...they're acting normal, they're certainly warm enough and you're taking good care of them!