Hi,
Recently on opening our opportunity entity records we were getting unsaved changes message.
To quickly get the list of all the fields
Open the debugger tool and put the following script in the console window
frames[0].Xrm.Page.data.entity.getDataXml();
Check this thread
http://stackoverflow.com/questions/32735019/dirty-form-with-no-dirty-fields-on-crm-2015-online
Hope it helps..