The Key is basically Immunity from being Nominated for Eviction no matter what your score is...unfortunatelly it's given out randomly :( You must click on it to use it
The apple is health to be added towards your health. By the end of the game, health will be added to you by the amount of apples you had in the game. Once again it's given out randomly.
And the check mark tells you how many points you're getting or something like that :S
Also...as requested by alot of players. Now you can see what score everyone else got