While there are people who may disagree with the government in their own minds, most know enough to keep their opinions to themselves. The few who still hoard and read books are eventually turned in by their neighbors and family, and the ones who don't hoard books but instead just think rebellious thoughts make no difference because they are scared to act. Faber is a good example of this last point; he saw the censorship coming but said nothing until it was too late, and now he just lives day-to-day, without purpose. Clarisse's family rebel against the government by just doing the bare minimum required and then thinking for themselves; Beatty, who represents the government, recognizes this as dangerous for society:
"Uncle had a mixed record; anti-social. The girl? She was a time bomb. The family had been feeding her subconscious, I'm sure, from what I saw of her school record. She didn't want to know how a thing was done, but why. That can be embarrassing."
(Bradbury, Fahrenheit 451, Google Books)
Outside the city, there are groups of "book people," hobos who walk along the railroad tracks and memorize books before burning them. By memorizing the books, they hope to pass their knowledge on to others. At the end, Montag joins the book people, and commits himself to helping them keep the content of books alive and moving from person to person.