Pretty inefficient when you can just slurp all the records in one request.
Make your create action know what to do when it receives a collection
document instead of an item document. Or break REST a little bit and
write a create_many action. As far as handling errors goes, it
depends entirely on what you need to do. You can run all the creates
in a transaction and return an error code if one fails. You can run
them all and make callbacks somewhere, notifying the source app that
one of the creates failed.