Undersea Kingdom

A Republic serial from 1936. The plot is basically the classic "Atlantis found" story. U.S. Navy Lt. Ray "Crash" Corrigan, Professor Norton and his son Billy, Joe the panicky sailor, and the Intrepid Reporter Diana Compton (and two other guys with a parrot, but they show up so little it doesn't count) journey to Atlantis, a "continent" that is under a dome of a gold/copper alloy. There they have misadventures trying to prevent the evil Unga Khan from destroying/conquering Atlantis, and eventually the "upper world."

See here and here for the episodes of Mystery Science Theater 3000 that featured the two installments of Undersea Kingdom.

Undersea Kingdom contains examples of:

Cliffhanger Copout: Crash and Billy are trapped on the top of a cliff as Unga Khan fires missiles at them, and we actually see the cliff collapse. Next episode -- They climb down the back before the recap ends. The Other Wiki's entry on Undersea Kingdom has a list of all the times this happens.
Color Coded for Your Convenience -- Well, it is black and white, but good guys = white cloaks, bad guys = black cloaks.
Compilation Movie -- Released for the TV market in The Sixties as "Sharad of Atlantis" (after the leader of the good "White Robe" Atlanteans).
Hey, It's That Guy! -- Captain Hacker is Lon Chaney Jr.
- The Volkite Mecha-Mooks were also used in other Republic Serials.
Intrepid Reporter -- Diana Compton
Mooks -- The Black Robes
- Mecha-Mooks -- The Tin Can Robot Volkites.
Schizo-Tech -- The Black Robes have robots and an earthquake machine, the USS Enterprise, flying torpedoes, view screens and ray guns. The White Robes only have flame throwers. The vast majority of everything else is swords, bows, and chariots.
Tagalong Kid -- Billy.
Those Two Guys -- Briny and Salty.
Yellow Peril -- Unga Khan, who is totally not Ming the Merciless.
You Fail Physics Forever -- Everything. All the time.