Divergent
Tris finishes her aptitude test and learns she isn't any one of the factions; she's far more, which means that she's divergent. Tori wants to make sure she gets out of the testing room as soon as possible so no one comes looking for her after the test results. This is a symbol that anyone who is divergent is a danger to the faction system that's been put in place.
Caleb
Caleb was born into the Abnegation faction of society, but chooses Erudite at the Choosing Ceremony. This is a symbol that he believes himself to be more elite intellectually than the family he was born into.
Turned on herself
Tris is being attacked by Four after Jeanine has turned on a manipulative system in his brain that makes him take orders from her. In order to stop him, Tris turns a gun on herself. This is a symbol that she's willing to give her life for the ones she loves.
Puddle
Tris goes into the fear simulation, and after being attacked by birds she falls into a puddle of water and escapes. This symbolizes her ability to reason far different than others in similar situations. This type of thinking and understanding [that the simulation was not real] allowed for her to respond differently.
Four's Tatoo
Four has a tattoo with the symbols of every faction on it. This is a symbol that he is a man who is out for unity, not one that seeks to bring prominence to his faction or allow any other to rise above and rule. He desires harmony within the factions, and it is a major reason he and Tris are on the same side and fall in love.
