Also, since he doesn't leave Airstrip One, we have no clue as to the state of the world — is Oceania real? Is it the entire world? Is there a Brotherhood after all? Nothing can be taken for granted, even the Info Dump book that pops up halfway through (especially the book, given that one of the Inner Party members claims credit for its authorship, and hands out copies).
It's a little bit of a stretch but we can't be exactly sure if Party even controls all of the British Isle. Could be half of it, just England or hell, maybe only London and its imminent surrounding. Which might explain whole "running out of resources" thing.
A common suggestion is that the 'scholarly' appendix on Newspeak is written in a manner that deliberately subverts this Downer Ending, given that it is written in the past tense...
When 1984 was to first be published in America, the publisher wished to remove the appendix, but Orwell refused to have it published without, saying that the book would have to be reworked if such a large chunk was to be cut out. This incident, along with a few hand-picked statements of Orwell around the time the book was written, form the basis for including the appendix into the work.
We explicitly never do learn if there's a Brotherhood or not. An alternate, admittedly optimistic interpretation would be that the Brotherhood did exist and that O'Brien was part of it, and that Winston and Julia's capture and death were in fact due to the latter's refusal to give up everything for the Brotherhood. Granted, that'd just make the Brotherhood no better than the Party. Or, alternatively, they just messed up somehow and got caught, and O'Brien couldn't say anything, because Big Brother is watching.
The Ministries may actually be true to their names from a certain point of view, and using The Party's way of thinking. The Ministry of Truth can be justified with doublethink, you may be able to consider the rations you are given by the Ministry of Plenty to be "plenty" from Big Brother's logic, the Ministry of Peace is justified through "WAR IS PEACE" and the Ministry of Love is where you learn to love Big Brother.
The Ministry of Truth manufactures truth as defined by the party. The Ministry of Peace makes a state of internal peace in Oceania by depleting resources.
Fandom Berserk Button: Lots of people think this book depicts a society where you're under surveillance all the time. You aren't, not all of the time. You just don't know when you're being watched and when you aren't.
There's also the misconception that everyone is watched and under the government's heel. Only government officials are watched; the 80% of the population that is the Proles are essentially "free" (hence the slogan "Proles and animals are free.")
Though the latter misconception about Proles being spied on is not completely unfounded as it is stated that the Party finds the brightest Proles and eliminates them.
Fan Wank: Much has been made of the Newspeak appendix being written in the past tense. Many think it points to the eventual fall of The Party (Thomas Pynchon even supports this interpretation in an introduction included with some editions), but Orwell never confirmed nor denied it.
Funny Moments: There is actually one in the film. During the Two Minute Hate, Julia goes so berserk with rage, throwing her shoe at th screen, O'Brien stares at her in incredulity. Knowing what we learn later in the story, it's downright hilarious.
Genius Bonus: In the final scene when Winston is playing chess in the Chestnut Tree Café, he picks up a White knight from the board and contemplates a move. The arrangement of the pieces on the chess board suggests that he is considering the tactic of going around and hitting the opposing Black army from behind. Only minutes later, the telescreen announcer reports that the Oceanian forces had just defeated the Eurasian enemy in Africa by using the same tactic.
Also, Winston's ulcerated ankle is a metaphor for repressed sexual energy.
The totalitarian society the book describes has been more or less realized by North Korea, which managed to create a state similar to the condition of Oceania a few years after the book was published.
One of the 3 super states in the book is the superstate of Eurasia, which practices the ideology of "Neo-Bolshevism" which as per the themes of the book, is a totalitarian ideology disguising itself as a populist one. As of now, there is an ACTUAL movement in Russia called National Bolshevism which not only sounds similar, but seeks to create a Eurasian super state led by Russia while maintaining a pseudo Communist government. They've been disowned by Marxists and Nationalists alike.
Also, O'Brien's speech to Winston and Julia in his apartment.
Plenty of people have commented on how the constant monitoring and citizens spying on each other makes Oceania look a lot like North Korea, but Winston's backstory also bears some disturbing similarities to the story of Shin Dong-hyuk, the only person to ever be born in a North Korean labor camp (for either the crimes of his parents or grandparents, he isn't sure which), and escape. Shin claims to have turned in his mother and brother for execution when they tried to escape. He did this because he saw them as competitors for food, and was hoping the guards would let him eat a full meal for the first time in his life (to this day he says he doesn't know what "love" means, and his entire concept of "freedom" is based around being able to eat as much as he wants.)
With a dose of Reality Subtext thrown in, Richard Burton was dying as the film was being made and his health was so bad that he had to wear support braces during rehearsals. It makes O'Brien's speech to Wilson about the frailty of the flesh and the strength of the Party much sadder in the case of Burton and more terrifying in the case of O'Brien.
In the 1984 film adaptation, John Hurt plays Winston, a man oppressed by a totalitarian government. 22 years later he plays Adam Sutler, the head of a totalitarian government in the film adaptation of V for Vendetta.
Mary Suetopia: A Straw Dystopia, where one of the members of State Sec even thinks that The Party will last forever, despite that in reality, there obviously would be corruption, revolts, sabotage, and failures in surveillance system, inefficiency and crises of economics, lack of professionals and social lifts which will lead to failures in the work of state... The list can go on.
Memetic Mutation: This is the work that informs modern life, with "Big Brother" and "Big Brother Is Watching You," "doublethink," "Unperson," "thought crime," and "thought police," and "Room101". While we're at it, there's the the war with Eastasia Eastasia is our ally. We were always at war with Eurasia. Really, the government in the novel communicates to the public almost entirely through memes.
Artifacts of the pre-Party times survive as memes too: "Oranges and lemons, say the bells of St. Clement's..."
"1984 was not an instruction manual!", is a common reaction to whenever a group is acting overly censoring.
Misaimed Fandom: If you think Orwell was solely attacking Dirty Communists (or, worse, liberals), you've missed the point. Fascist totalitarian regimes and religious theocracies can grow from other movements as well. The reverse is true, as well.
There are those who believe the novel is an attack on socialism, ignoring the fact that Orwell was a committed socialist.
Some people consider the character of Emmanuel Goldstein to be a symbol of rebellion against tyranny because of his status in the book as a boogeyman for the Party. However, it's likely Goldstein was based on Leon Trotsky, whom Orwell considered not much better than the Communists he rebelled against.
Nightmare Fuel: Vicious propaganda, endless war and all, culminating in Winston's hideous Mind Rape at the hands of the Ministry of Love, with the last few lines deserving to be in its own category of terror.
Room 101 embodiesNightmare Fuel, as it takes the biggest fear a person has and exploits it fully.
Sci Fi Ghetto: Many literature professors will get very angry if you call this "Science Fiction," even though it's set in the future, with a level of surveillance impossible at the book's writing central to the plot and tone and the climax clearly relying on some sort of ultra-sophisticated psychological profiling.
The otherworldly pyramid architecture of the Ministry buildings. While not necessarily containing an outright sci-fi element, their description evokes a futuristic, utopian feel.
In the final chapter, a sweet memory floats into Winston's mind from his childhood about a happy afternoon when he played Snakes and Ladders with his mother. It's a memory he would've treasured earlier, but now he pushes it out of his mind, declaring it to be false.
The fact that some elements in the book — including constant surveillance of citizens and disproportionately severe punishment for the slightest interest in rebellion — have become elements of some Real Life governments is horrifyingly depressing.
True Art Is Angsty: The book is considered one of the greatest ever written, and it's one of the most depressing ones you'll ever read.
Values Resonance: As noted in Harsher in Hindsight, The War on Terror created a world where government-enforced surveillance gets uncomfortably close to what Orwell wrote. Subverted in that the proliferation of video capture devices have been used against authority as well.
The Woobie: Winston and Julia, especially in the movie.