Doctor Who/Recap/S1/E06 The Aztecs

Ian: Where did you get hold of this [brooch]?
The Doctor: My fiancée.
Ian: I see ... your what?
The Doctor: Yes, I made some cocoa and got engaged.

Historical time again, as the TARDIS materialises inside an Aztec tomb. Upon emerging, Barbara is hailed as the reincarnation of the goddess Yetaxa. Oh, and door to the tomb shuts itself behind them.

Despite the Doctor's warnings, Barbara seizes the opportunity to influence history. Her intentions are good—she decrees an end to the practice of Human Sacrifice—but she instantly makes one of the high priests suspicious of her alleged divinity, and pitches the other one headlong into a crisis of faith. Barbara finds that even a goddess can't effect social change by fiat.

The Doctor accidentally gets engaged to Cameca, an Aztec woman for whom he makes a cup of hot cocoa, while Ian is forced to fight a judicial combat. He wins, and meanwhile the Doctor has lashed up a pulley wheel to open the massive tomb door and let them back in to escape in the TARDIS.

Watch it here.^{[dead link]}

Tropes

Accidental Marriage
Aztec Mythology
The Bad Guy Wins: The villain gets rid of the pesky false god, his rival, and he gets to keep sacrificing.
Bookcase Passage: the innocuous-looking stone in the town square
Breaking the Fourth Wall: Slightly at the end of the first episode, as the evil high priest looks straight at the audience when he vows to destroy Barbara.
Evil Versus Evil: Cortes' conquest of the Aztecs. Barbara wanted to prevent the Evil Versus Evil aspect at least.
God Guise
Human Sacrifice
Large Ham: Tlotoxl. Who knew Richard III was in fact an Aztec high priest?
Mayincatec: Feathered headresses, as much of a step pyramid as you can fit into a 1960s Who budget, and a priest obsessed with human sacrifice.
Nice Hat: Tlotoxl again.
Pressure Point: How Ian wins his battle against Ixta, only using his thumb.
Right Makes Might
Shown Their Work: Notably, Mayincatec is averted, as the screenwriters evidently did a bit of research.
The Unpronounceable: The cast members never seemed to have reached a consensus on how 'Tlotoxl' is actually said.
- Furthermore, no one actually gets it right - it would have been more like "Tlo-tosh-l".
The X of Y: All four episode titles follow this format.
You Can't Fight Fate: "You can't change history, Barbara. Not one line."