Since there was recently a post about confusion on mucking a hand, here is one of my favourite horror stories from live play, which happened recently at an omaha final table. Thankfully it didn't involve me. It did involve the two chip leaders though.
Chip Leader 2 (to my left) raised preflop, and was called by Chip Leader 1. The flop comes down, and CL2 bets, CL1 moves all in and CL2 calls. CL1 says "were you on the flush draw?" CL2 says "yes." The turn and river were dealt, then CL2 gets up and shakes the hand of CL1, as the dealer is mucking the cards and pushing all the chips to CL1. He is about to leave when another player says "hang on there were three hearts on that board" Another player who was paying more attention than I was, confirmed exactly that. The board hadn't paired and these are two players who know what they are doing and are rock solid. If they said there were three hearts on that board, then there were. One or two others confirmed they were right. CL1 called for a ruling. He considered the pot was his as the cards were mucked. The ruling surprised me.
The ruling was, as the next hand had not started, CL2 was the winner and should receive the chips as he had made the flush. CL1 spent ten minutes blowing his top. The dealer and the rest of the players had to sort out exactly how many chips were in that pot as they were now thoroughly mixed in with the stack of CL1. I closed my eyes and had some rest in the corner. It was about 2.30 am and had been a long night. The dealer took compassionate leave from the game and was replaced. I think he automatically assumed CL2 had won the pot when he got up to shake hands and leave, so I don't blame him at all, although CL1 was seething angry. Some sort of justice was done as they ended up being part of a three way split when I was knocked out in 4th.