* One of the rebels who you first encounter, and who is severely injured, is named Winston. Winston was the same name of the protagonist in the novel 1984, which inspired City 17's harsh brutality of civilians, and heavy surveillance.
* Besides the drain on the world's resources by the Combine, something which was even toned down from miles upon miles of dead earth in the beta/leak, there's also ''insane'' amounts of irradiated water and waste filling up entire canals and areas as Gordon rides around on the airboat. The HEV Suit protects him, sure, but what about all the rebels and their stations that are built around these radiated materials? They wear nothing but civvies or stolen vests and clothing, and the very person who prepares the airboat for you is just in an open end of the canal, on some wood boards inches above entire waist-deep pools of the stuff.
* Those weird screams headcrab zombies make? [[https://www.youtube.com/watch?v=md1afDGmUXA They're in English, reversed.]] Play them backwards, and they're actually ''[[IHaveNoMouthAndIMustScream the anguished screams of the headcrab's host.]]'' That's right, headcrab zombies are not only not dead, ''they're fully aware of what they're doing and helpless to stop themselves.''