If a character discusses subversive views/things that aren't normal/idyllic (like the mannequins) in the presence of their neighbors, if it's a more minor thing like "I wish we could leave" the neighbors will shush them. If it's a more major thing like talking about the mannequins, first neighbors will tell them that they're crazy and that they're watching too much sci-fi, but if they persist, the neighbors will report them. Discussing subversive thoughts/conspiring/expressing leftist views/talking about abnormal events on the network or over the telephone will always get a character caught.

In general it's player discretion, and players are trusted to be realistic about it - talking about these things in the open around a bunch of people will inevitably result in someone saying something. Players are also welcome to have characters think they're in the clear and... not be in the clear for reasons they don't understand.