The other day during a Mets game, an interesting play happened. A foul ball went behind the backstop, rolled around in the screen for a long time, then slowly rolled back onto the field, behind the catcher and ump. Meanwhile, the pitcher had received a new ball. The next pitch was almost a passed ball, which led the announcers to wonder: If it had been a passed ball, what would happen if the catcher ran back and didn't know which ball was the live one and/or picked up the wrong ball and put it in play?

This verything happened in a Cubs Phillies game (I think) several years ago. Two balls were in play on the infield or something like taht and both were being thrown around to get an out. The Cubs recorded an out during the mayhem and the Phillies were playing under protest. They, the Phillies, won the game so they withdrew the protest.....