Hunger Games Plot Twists

1. In the mine explosion that supposedly killed Katniss's father, Mr. Everdeen had been clever enough to find a way out. He saw his family grieving for him and ran away to the Capitol where he had plastic surgery, had his eye color changed, and changed his name to Cinna.  He got a job as a stylist for Katniss, and that is why he asked for District Twelve.  This could be the reason Cinna and Katniss were so close.
2. When Foxface was thought to have been killed by nightlock, she had really created a dummy, and pretended to steal and eat the berries.  The Gamemakers never found out, and created the mutt like her because they thought she was dead.  But she was still in the woods surviving and stayed alive until the new Republic of Panem destroyed the arenas. 
3. Everyone thought that Cato had cut Peeta, but really, Peeta cut himself and acted like it was Cato.  Even Cato thought he had cut Peeta.  By doing this, Peeta was guaranteed to get attention from Katniss.  But he didn't plan to get blood poisoning.  So to get a fake girlfriend, Peeta had almost taken his own life.

If you think of another one, post it as a comment and I will add it.