30 was the change!
It was 21 in the book.
Not a movie that needed remaking!
Yup, they changed it in the movie because they simply could not find enough young actors to fill the extra roles. Plus they wanted certain actors who were over 21.
That’s one way hollywood has changed. Getting enough young actors is no longer a problem.
other differences:
There are no domed cities in the book. The world is inhabited much as it is now. Sandmen guns are much more devastating, having 6 types of ammo to choose from: Homer, Ripper, Nitro, Vapor, Tangler, Needler. Most are obvious what they do except ‘Ripper’, which I have never figured out.
IIRC, the “Ripper” shredded the target’s nervous system. Painfully.
I’m pretty sure that was what the “homer” charge did when it hit. Burned out all the nerves. The Ripper was never explained. I think Logan shot a stray lion with the Ripper and didn’t take it out, Francis is described as using a Ripper shot against the Cubs but there’s no explanation of the effect.
Nolan’s novel was about the social effects of the youth-obsessed culture of the Baby-Boomers – at some point young people worldwide reached “critical mass” and decided to outlaw non-youth. Worldwide. This interesting and timely SF concept was completely lost in the movie, which gives us only this one hedonistic, post-apocalyptic domed city where the age limit is, apparently, nothing but a population-control measure – a rather ordinary concept, by comparison. 
Whether the cutoff age were 21 or 30 or even 35, a high-tech society with no middle-aged or old people could never work; it would have to be a primitive agrarian society like in Children of the Corn (I mean, part 1, and King’s original short story). Just think about how long it takes to get really proficient in any complicated skill or profession.
Maybe today it seems ordinary. Maybe it was ordinary even then, but it was still of a piece with the clenched-ass Malthusian pessimism that defined early 1970’s cinema. Logan’s Run and Soylent Green would make a great double feature.
Hey, when Deckard and Rachel get into the elevator where the heck are they going?
Cold Comfort Farm
It’s been a very long time since I read the book, but my impression was that most everything was handled by the Thinker (the computer complex in Crazy Horse Mountain that ran the world). So the need for “complicated skills and professions” would be greatly reduced.
It was fairly obvious that the world of LR had an economy—Logan is charged for his visit to the glasshouse at the beginning of the book—but except for Sandmen and the police, most people seemed to be more involved in hobbies than professions.
I just thought of something else about feeding all the Citizens…
we’ve just assumed all those cats are pets of the Old Man. Maybe they’re his cattle herd.
You could well be correct - I haven’t read the book in twenty years or so. (Mind like a steel sieve, that’s me.)
So they have meat and dairy covered…
“You tried to milk him? Didn’t you, you bastard!”
And I’ll bite, Otto…
Why didn’t Quint have to die?
[spoiler]On the practical end he was bitten in half.
On the film analysis end he represented the antithesis of Hooper and marked the difference in past and future means of dealing with the problem. It took the action-oriented outsider to actually use the tools at his disposal (new scuba tank and old rifle) to combine the two and ‘deal’ with the problem.[/spoiler]
I have nipples. Can you milk me?
Silly, boys don’t give milk. You’d have to change your name to NoClueGirl.
It hit me like a lightning bolt upon a viewing, immediately after Brody’s famous line, “You’re gonna need a bigger boat.” They had a bigger, or at least a better, boat. Hooper’s. A completely modern boat loaded with state-of-the-art equipment, versus The Orca which whatever its virtues had seen better days. Had Brody gone as Quint’s charter passenger and Hooper followed in his own boat, Quint very likely would have survived.
Present them.
No, actually,
When Logan confronted the stray tiger, the Ammopac in his Gun was down to two shots: Homer, and Tangler. The flat statement was made that a Homer was useless against animals, so Logan shot the tiger with the Tangler.
I’d also like to take the opportunity at this juncture to point out my Highly Unofficial Logan’s Run FAQ.
Maybe they changed it because the “Outlaw everyone over 30!” concept had already been used several years before in Wild in the Streets.
Oh, I rarely get the chance to mention this, but my uncle was an extra in Logan’s Run. He is still alive.