In Catching Fire, the second book of The Hunger Games series, the 75th Hunger Games take place. There's a few events leading up to them that make me wonder if the rules of the 75th game were known in advance.
Plutarch Heavensbee, the new game master of the Hunger Games, shows off a watch to Katniss, and later, it's revealed that the watch was a hint about how the arena in the 75th games worked. The 75th Hunger games saw Katniss being sent back to fight again in the arena. Did Plutarch know that Katniss was going to be participating again, which is why he showed her the watch? If he didn't, why did he show her the watch with the clue to the games? Katniss wouldn't have been able to communicate any information to anyone in the arena otherwise.