How about this one - I got bowled, for a very scratchy 7, earlier in the season, and I thought "ok, fair enough, good ball on a bad pitch", and walked off. My team-mate who was at the non-striker's end later told me (as I had noticed when I was there) that that particular bowler had been bowling no-balls all day and the umpire had only call about 3 of them. He said the ball that had got me was a no-ball by about 6 inches over the crease, which was a little frustrating.
About 3 weeks later, I spoke to my coach who was umpiring at the other end in that game, and he said that when I got out, and as I was walking off, their umpire had come up to him and said "that was a no-ball I'm afraid, but I forgot to call it in time - he'd already started walking off. Sorry". That was so infuriating - I was about 10 feet away from him, why didn't he just call me back? And how can you "forget" to call a no-ball? Grrrrrr.....