Scales of Justice
We see the scales of justice hanging behind a committee, as they say they've found no conspiracy in the assassinations. The symbol is that they are meant to judge equally, but the scales are highly imbalanced.
Black Briefcase
Joe finds a black briefcase in the Sheriff's drawer in his home after the Sheriff has died at the damn. The symbol is that the Sheriff is part of a much larger conspiracy that Joe has just found his way into.
Questions
Joe takes the Parallax's questions to have them examined. We see the questions in frame and the content of them are symbols that someone has created a test that allows them to find emotionally unstable people as the questions steer people towards emotional reactions.
Aggressivenss
Joe throws his pot on the floor while a Parallax employee is in his apartment. He's being incredibly aggressive and reacting emotionally. The symbol is that this is what Parallax wants in their corporation and Joe is giving it to them.
Human Engineering
At the department of Human Engineering at Parallax we see Joe watch a film they created. The film is a symbol of brainwashing by big corporations in order to prey upon the weaker people in society to do their dirty work.