Here's a lovely "misclick." In this game, I'm going for a Scrying Pool engine. My opponent doesn't even have a potion, so once I buy my ninth Scrying Pool, I alone have control over the depletion of the last pile (Pawns and Grand Markets were empty, but no other piles were close). I have a decent position here, since I'm able to end the game with a lead as long as I can buy the last SP and enough VP; but my opponent doesn't have that option.
We're at my Turn 16 now:
My SPs are overdrawing my deck at this point, so I have my deck in hand with some GMs and Pawns left to play. Almost on auto-pilot, I play an Upgrade, thinking I'll trash the Potion into a Duchy for some extra points. Once I clicked to trash the Potion, I realized my mistake. Without a Potion, I can't 3-pile on this turn, possibly opening the door for my opponent! I'd have to buy the Potion back that turn and hope to get another turn with the option to end it on a win.
I was talking to my opponent on Skype at the time, so once I did that, we both talked about how screwed that made me for a bit. Before that, I had enough to just buy two Colonies and an SP, which would have been enough to win; Trying to maximize points, I just potentially threw away the game!
Then I realized there was still a way around it...
http://councilroom.com/game?game_id=game-20130113-203126-e236a2b7.html