In one scene, Snowden is learning how the NSA spies on people "lawfully". His instructor is teaching a bunch of newbie spies about this, and the instructor says something that is blatantly false but sounds kind of true if you don't go too deep into it. He claims that this spying is legal and constitutional.
Another aspect here is that experienced hackers like Snowden have probably trained their memory and their capacity for forming conceptual inferences to be much more powerful than those of the workers teaching the class. The instructor may expect everyone to believe what he says, even when exposed to differing information, until people like Snowden demonstrate otherwise. Because it worked in the past, before you needed to have incredible cognitive skills to be effective at international conflict.