First, I would not expect that this would ever happen as I always review all project specs, time requirements, and deadlines prior to starting any new assignment to ensure my work is done on time, within budget, and that it meets all project specifications. If it ever were to occur, I would bring the issue to the attention of my superiors and ask for a realistic extension to make sure the project met all specifications. I would review my project planning process to see what went wrong, why the project was not done on time according to specs and take steps to make sure it never happened again.