Kids in the Alley
Lowry sees kids holding another kid at gunpoint with another wrapped in a bag. Lowry doesn't do anything to stop them or comment on the situation. It's a symbol for a lack of awareness in society for what kids are doing and also it symbolizes the affect the culture has on the kids as they reenact what they see in their day to day life. And this scene is what they see happening to them and their families and neighbors.
Tea
After discovering that Buttle should have been Tuttle on a Ministry of Information form Kurtzmann is full of anxiety because he has to do something about it. That is until he learns another department made a mistake then he doesn't care. He offers Sam tea, and the tea is a symbol of the lack of care one shows for another human being's well being. That they only care if it has any affect on them.
Plastic
We see Sam's mother in the process of getting wrinkles removed from her face. Gilliam gives us a literal symbol of plastic by showing a closeup of her face wrapped in saran wrap. It's stating that no matter how ridiculous one actually looks they believe they are more beautiful because of the lies they are fed from the people performing the procedure, and the fact that everyone else is doing it so it must be good.
Paperwork
Sam is able to stop Central Services from entering his apartment by asking for a specific form that has to be filled out before they can repair his air conditioner. The paperwork symbolizes the bureaucracy within the city. That the process to get something fixed takes so long that nothing gets taken care of in an appropriate time frame. Thus the city is falling apart from this long string of checklists that must be done in order to do anything.
We Don't Make Mistakes
As workers place the floor back where armed officers tunneled through to arrest Buttle they tell the neighbor upstairs that they don't make mistakes. Just as they say this the piece they cut to fix the floor falls through into the Buttle apartment. This is a symbol that the Ministry of Information feeds lies to such a rampant degree that their employees believe everything they say even though they are wrong in many instances.
