Booked a trip for myself on points, then a week later decided that I would bring hubby and two girls along too. So I went online and booked their trip on a separate pnr.
It was only when we arrived at the airport for our return flights that we found out, after much consternation and digging, that I had booked their flight for a day later than mine. $400 and some long phone calls later we headed home on different flight!
Felt very, very stupid.