Mask
Kylo Ren wears a mask throughout most of the film. His mask is a symbol of his desire to disconnect from the world and stay hidden in his pain, which he has come to believe is the source of his power.
Blood Streaks
We watch as a stormtrooper smears blood on another before dying. It is Finn who the blood is wiped on, and once it is on him he instantly begins to realize the horror of war and killing. The blood is a symbol of a soldier who's been brainwashed awakening to the reality of his actions, and that there is real blood on his hands for what he has participated in. Finn can no longer participate in this carnage.
Map
BB-8 finds a piece of a map to the location of Luke Skywalker. It is a symbol that there is hope for the Republic as the Jedi still exist and could fight for the cause.
R2-D2
On D'Qar, BB-8 finds R2-D2. Finding R2-D2 after such a long time is a symbol that the force has not only awakened but is piece by piece bringing together the necessary pieces in order to fight and defeat the First Order.
Lightsaber
Rey finds a lightsaber locked away in a chest in Max Kanata's basement. It belonged to Luke Skywalker, and it called out to her. The lightsaber is a symbol that Rey is called to be a Jedi.
