The rotten Big Apple here represents the worst that could happen under a harsh, uncaring government. Along with that comes a theme of mistrusting authority and "the Man." There are no real heroes; the closest thing is a commando-turned-robber, motivated entirely by self-interest (or other people coercing him). Even he is disgusted by the callous attitude of the hostage US president (and, by extension, the society that president represents).
Gunfire, explosions, beat-downs, and gladiatorial death bouts with fists and clubs. A severed head. Characters stuck with arrows and knives. Implication that high-tech tiny time bombs are implanted in someone's head. A hijacked plane crashes into a Manhattan skyscraper as in 9/11, but only a radar-readout is shown.
Blink-and-you'll-miss-them bare breasts, as NYC prisoners manhandle a girl. Low-cut outfits for the leading lady. Plissken makes an angry joke about "playing with myself." He has a suggestive tattoo around his crotch.
The s-word, the f-word, "a-hole," "Jesus Christ," "bastard," SOB.
Chock-Full-a-Nuts and Coca-Cola signs visible.
Tough-guy cigarette smoking. Drunken-derelict type characters in a skid-row setting, mention of junkies.