“Yes” means close enough for folk lore, or up to spot on. Based on KGS, but for further detail, see bearflag70.
The Superstition Mountains - a mountain range east of Phoenix, AZ (or is it south?)—Yes, east. Allegedly contains the Lost Dutchman gold mine.
Krakatoa - Volcanic island east west of Java, Indonesia that went KABOOM in the late 19th century.—Yes
El Dorado - This is a movie, isn’t it?—It may be. Believed in by the Spaniards exploring America. Heavily armed foreign men arrived at your town conveying the question, “Where’s all the gold?” You convey, “Over beyond there, lots of it!”
The Ready Bullion - Sounds like a tavern somewhere during the Gold Rush.—The Alaska one. A hard-rock gold mine near Juneau, Alaska. Obscure, inserted because I like the name.
Mt. Shasta - Big active volcano in No. California at the southern end of the Cascades mountain range. Second highest mountain in California.—Yes, dominates the area, cool to see
The Continental Divide - The line that divides North America between the Pacific drainage basin and the Atlantic/Arctic/Gulf of Mexico drainage basin.—Yes
The jumping-off point. The California Trail, the Oregon Trail. - St. Joseph, Missouri?—Plenty close. Jumping-off point in Independence, MO, where the CA & OR trails began, so where pioneers bound for the West Coast felt they broke with civilization. The trails diverge later.
The Back of Beyond - not a clue…this is the fake one, right?—Fake, yes. Phrase in (British) colonial days to describe some remote little-known area of the world, cost/benefit ratio unknown.
Nome - Small town in Alaska, on the Bering Sea. One of the most isolated towns in the U.S., you can only get there by airplane or dogsled.–Yes. Had an epidemic, needed serum.
The Great Rift Valley - Great big valley in eastern Africa running north/south between Ethiopia and Tanzania. Formed by two continental plates slowly drifting apart. Some of the earliest human-like remains were discovered there.–Yes
Land’s End - The far southwestern tip of Great Britain.–Yes, & a good name for that point.
Babylon - Where modern-day Iraq is now.—Yes
The Punjab - The chunk of India between Bangladesh and Myanmar.—Yes, great fertile valley, the Indus River and its tributaries.
The Ganges - The main river in India.—Yes, another great fertile valley.
**The steppes ** - I think this is the area between Siberia and Afghanistan, used to be the Soviet Union but now broken up into Uzbekistan and Kyrgyzstan and a whole bunch of other -stans. Similar to the Great Plains of the U.S., but drier and more desolate.—Yes, short-grass prairie there.
The Altai mountains - If you meant to say “Atlas Mountains” and misspelled it, then it’s a mountain range in North Africa (Morocco & Algeria to be precise); otherwise I’ve never heard of it but I’m guessing it’s somewhere betweenthe Steppes of Asia and Siberia.—No typo, they are along the border of Russia and China/Mongolia/Kazakhstan
Siberia - Where the Gulag prisoners were sent. Comet crashed there in 1902.—Yes
Tibet - Predominantly Buddhist province in[disputed] southwestern China. Very, very high plateau at the base of the Himalaya mtns.—Yes. Location of Shangri-La and all kinds of mystic ideas.
The Danube - It’s blue. River in Eastern Europe, runs through Vienna and Budapest and empties into the Black Sea.—Yes
The Bight of Benin - sounds like an African porn star.—Got the right continent. It’s the gulf below the bulge of west Africa. “Beware, oh beware, of the Bight of Benin; for twenty come out where one hundred went in” from when Europeans were trying to gather wealth there. A lot of malaria and so forth.
The Big Muddy - Wasn’t this a nickname for the Alcan Highway? Or the Mississippi River? I forget which.—Hey, you one-upsed me there! It’s usually the mighty Missouri, but it turns out the Big Muddy Badlands exist in Saskatchewan north of Montana.
The Northwest Passage - Nobody ever found it.—right, and they tried, too. Wanted a sea passage through the N.Amer continent to the West Coast and Orient.
Ixtaccihuatl - Gesundheit.—Thank you. Volcano near Popocatepetl (other volcano) near Mexico City
Macchu Picchu - Pokemon?–Snork! Deserted stone city high in the remote Andes, built by the Incas or equivalent, not discovered until this century–oops I mean the last century, 1911.