The Apple
The apple that Oppenheimer poisons in an attempt to kill his professor is symbolic of forbidden fruit. For Oppenheimer and those involved in the development of the atomic bomb, they were initially eager to develop the weapon (much like Oppenheimer was initially eager to poison the apple). However, after thinking more about their actions, the men become disillusioned and disgusted with their creation, mirroring Oppenheimer's decision to throw away the apple, preventing it from wreaking havoc on anyone who eats it.
Oppenheimer's security clearence
Oppenheimer's security clearance, which he initially struggled to obtain because of his past, symbolizes his fractured mind and relationships. For much of his life, Oppenheimer struggled to keep his pulse on reality and building meaningful relationships with people around him. His security clearance embodies those struggles: initially, he struggled to obtain one (much like he struggled to find a woman to marry), but he later gets his security clearance and finds a wonderful woman to marry. Eventually, however, he loses his security clearance as a result of maleficence, just like his relationship with his wife was harmed.
Testing
Throughout the film, Oppenheimer and his team tests their creation, hoping to prove that their invention has merit and could be executed on a grander scale. This motif emphasizes the profundity of their creation and their dedication to perfecting their creation. It also shows the transformative effect the atomic bomb could have on the team and world more broadly.
Alcohol
Alcohol symbolizes loss of autonomy and control. Kitty, Oppenheimer's wife, becomes an alcoholic at the end of the war. Not only that, Oppenheimer's lover, Jean Tatlock, was an alcoholic. Both women had one thing in common: they struggled with feelings of inadequacy brought about by a sense that they weren't in control of their own emotions. In the context of Oppenheimer's life, alcoholic tendencies destabilized him and reinforced his desire to remain in control of every faculty of his life, contributing to his perfectionism.
