The pilot wasn't having much luck on his flight review. As he and his instructor were about to depart, the airport weather went from a manageable SCT006 to BKN006, requiring an IFR clearance. Since they had planned to depart VFR, they didn't file an IFR flight plan. To top it off, the part-time tower was closed.
This is a companion discussion topic for the original entry at https://www.avweb.com/flight-safety/technique/pop-up-clearances