On the orders page, if you edit an order to extend its order’s cancel date (i.e. from 03/01/14 to 04/01/14), the “e” for the respective order will turn red indicating there has been an extension. You can also hover your mouse over the “e” for more details.
The order date value under the cancel date column will also appear in red. This will easily signify that the order was extended from the original date.