One of the thing I found very odd about Gamma World as a kid was that the currency from before the End -- the domar -- was still recognized and valued in the post-apocalyptic world, even if it was worth one-fifth that of gold. Like most modern currency, the domar, as described, has no inherent value, since it was made of some kind of indestructible plastic. Without the power a government to back it, what value would it have, especially 150 years after that government had ceased to exist. Consequently, we tended to treat domars more as curiosities, of interest to historians and the Restorationists rather than of broad use when trying to make purchases in most settlements.
Healing in Gamma World is slow -- 1 hit point per day of inactivity and rest -- but not as slow as in OD&D, where it's 1 hit point every other day of inactivity and rest. Of course, Gamma World characters tend to have more hit points that most OD&D characters, which may explain the difference. There are also various medical devices and medicines that increase the speed and efficacy of healing and these, too, have an impact.
I've already discussed the inheritance rules here.
Gamma World postulates the existence of a "common tongue" in post-apocalyptic North America, which seems reasonable enough, although the rationale behind its existence is odd:
Because so many of the mutants of GAMMA WORLD use telepathy, and so few Pure Strain Humans are left, a common language has evolved among all speaking beings and creatures.I suppose the text means to say that a common tongue came about out of necessity, but it's phrased oddly. Regardless, computers may or may not be able to recognize or learn this new common tongue, as the referee decides. In my own games, I don't think I ever used language barriers when dealing with computers but I frequently used concept barriers, because the computers came from a highly technological world whose assumptions were very different from those of the PCs.
A distinctive feature of Gamma World is the presence of so many robots in the rulebook. Nearly three whole pages of the rulebook are devoted to the topic, which is a sizable amount, given its brevity. It's another way that the game emphasizes that its apocalypse takes place in the future rather than the present day. In describing robots, there are a couple of interesting rules conceptions worth noting. First, Gamma World retains a strong concept of armor class as strongly connected to the materials from which a type of armor is made. For example, duralloy typically provides an AC of 2 or 1, though a robot constructed from a combination of duralloy, plastic, and/or glass may have a lesser AC due the presence of those other, weaker materials. Likewise, hit points are directly related to bulk, with robots gaining 6 hit points (1 Hit Die) per cubic meter of size. Furthermore, every time a robot loses one-quarter of its total hit points, it also loses one-quarter of its functionality. The latter's a particularly interesting conception that could serve as a springboard for anyone looking to add "death spiral" mechanics in D&D.
In Gamma World, there are generally three types of robots: bots, robotoids, and borgs. Bots and robotoids are similar in that they both are programmed for limited and specific action, there difference being largely in appearance. Robotoids are humanoids, while bots are not. Borgs, on the other hand, are artificial intelligences. They possess inorganic brains that function like those of humans, right down to being susceptible to mental attacks and the ability to degenerate into insanity. There are also larger -- building-sized -- A.I.s that function more or less like borgs do, except that they lack "bodies" and thus function primarily through lesser robots that they control.