Make sure you leave your accommodation clean and tidy. Hand the keys in on the due date and ensure all bills are paid up in full. Irrespective of how you have found your accommodation it may be used by the company again in the future and how you leave it may well get back to your internship company – potentially damaging the good work you did in creating a quality and lasting impression.
Set up a mail forwarding or redirection to ensure you receive any mail sent after you have left.