What dealers will do on non-business days, or after hours, is they will complete the deal using the best information they have, but they will include in the things you sign, a document that essentially states the deal is not final until they can assign the loan and you agree that if in the end, they can't assign the loan you will bring the vehicle back.
That way they can work the financial institutions the next business day possibly improving things for themselves. Or on rare occasions, they may find that they can't complete the deal, and they'll need the car back.
