At checkout, you have to select a checkbox stating that all information on your paper product is correct and that you are ready to print your work. We do not double-check orders for mistakes before printing- what shows on your PDF/review page at checkout is what will be printed.
Please note that you do have a 2-hour window once you have placed your order to cancel.
If you do notice a mistake on your order that you did not realize was there, please contact customer support at firstname.lastname@example.org. We are happy to offer assistance!