Red Hoodie Symbol
The red hoodie that Hayley wears is a symbol to her of the job she has to do. It is her superhero cape, and a symbol of her status as a vigilante avenger, ridding the world of the men who have committed rape and murder and gone unpunished.
Girl Scout Symbol
As Hayley holds Jeff prisoner, she answers the front door to a little girl selling Girl Scout cookies. The fact that the child is allowed to come over to Jeff's house by her mother who lives next door is a symbol of Jeff's outward normality and veneer of being a thoroughly decent person who is safe to be around children.
Fake Castration Symbol
Hayley fakes castrating Jeff. This is a symbol of the fact she is capable of anything when it comes to avenging Donna Mauer's death. Although she does not ultimately go through with her threat, it is clear that this is something she is capable of doing.
Restraining Jeff Motif
Jeff seems to spend a great deal of the movie tied up or restrained by furniture. This is a constant motif in the movie and also a symbol of the way in which it is almost impossible to catch men like him permanently. Hayley appears to have him restrained but he gets away and threatens her again. She outwits him, shoots at him with a stun gun, and he wakes up restrained by a larger piece of furniture. A second time he frees himself, and a second time he is recaptured. This shows the back and forth between law enforcement and sex criminals.
Trophies Symbol
Jeff has a photograph of Donna Mauer which is a trophy. Typically murderers will keep something from their victims as a symbol of the murder so that they can think about it each time they see the item. In this case it is the actual picture of Donna that acts as a symbol of Jeff's crime.
