Doctor Who has a long and noble history of attempting to convey history to its young viewers. It has not always been completely successful, however. Here are a few stories where they dipped into history -- but didn't get the history quite right.
On Doctor Who:
The TARDIS arrives in Tombstone, Arizona, just as the Clanton brothers arrive, looking to kill Doc Holliday for killing their brother. They promptly mistake the Doctor for him, because they don't know what he looks like. Wyatt Earp's brother Warren is killed, and Wyatt swears vengeance. This leads to a gunfight at the O.K. Corral. The Clantons, aided by Johnny Ringo, face down Wyatt Earp, Virgil Earp, and Doc Holliday; the Clantons and Ringo are shot dead, and our heroes take the opportunity to slip away in the TARDIS.
The depiction of the shoot-out in "The Gunfighters"
Of all the historical dramas in the first few seasons of Doctor Who, this is probably the least accurate. The Clantons weren't seeking to avenge a slain brother (yet), and there was no chance of them mistaking anyone for Doc Holliday, whom Ike Clanton had been busy trying to frame for some time. Warren Earp wasn't involved, and lived another 20 years. And the actual players at the gunfight were Doc Holliday and Wyatt, Morgan, and Virgil Earp facing down Frank and Tom McLaury and Billy Clanton (the latter three all died). Ike Clanton, killed in the shoot-out on Doctor Who, fled the fight in real life and continued the feud. Infamous cowboy Johnny Ringo wasn't at the gunfight.
The three dead Cowboys after the real gunfight: Tom McLaury, Frank McLaury, and Billy Clanton
As a side-note, set reports from the BBC's filming in Almeria, Spain (location of classics like The Good, the Bad, and the Ugly), reveal that there will finally be a second Western on the show, probably the third episode of Series 7.
The Masque of Mandragora
On Doctor Who:
The Fourth Doctor and Sarah Jane battle a living energy, the Mandragora Helix, in 15th-century Italy. The Helix intends to take over humanity at this delicate juncture between superstition and science, between religion and reason. There is a power struggle going on in the duchy of San Martino, and the rational, science-minded Prince Guiliano is accused of being a witch. In one scene, he explains to Sarah Jane his theory that the world is actually a sphere, as if he expects her to be shocked.
The conversation between Prince Guiliano and Sarah Jane starts at 2:50
Or would he have expected her to be shocked? Science was more advanced in the 15th century than usually given credit, even in Western Europe. Astronomy was fairly advanced, and the size and shape of the Earth had been known since antiquity; Eratosthenes even computed the correct circumference to within 2% of the actual value around 200 BC. The work of Dante Alighieri, who wrote his epic work The Divine Comedy over a century before reflecting the mainstream view of both church and secular authorities, clearly references a spherical Earth. So rather than being ahead of his times, Guiliano is behind them.
A diagram of Dante's depiction of the spherical Earth; it's a cutaway view, intended to show the structure of Hell underground
City of Death
On Doctor Who:
Visiting Paris, the Fourth Doctor and Second Romana stumble upon a complicated plot to steal the Mona Lisa -- by an alien who has six copies in his basement that have been bricked up since 1508, right after Leonardo da Vinci painted them. The alien plans on using them to bankroll a time machine that will get him back 400 million years, so he can prevent an explosion in the spacecraft that is carrying his entire species. The Doctor has to intervene, because that spacecraft's explosion is also what jump-started life on Earth.
Conclusion of the serial. As a bonus, watch for John Cleese and Eleanor Bron's uncredited cameo at 7:14; they appeared as a favor to their friend, script editor Douglas Adams
Perhaps the Doctor didn't need to worry quite so much; 400 million years ago, life on Earth was already well established. Life on Earth started about 3.5 billion years ago. That's just as well; our heroes would have found it very difficult to breathe if they had gone back to stop Scaroth just before the start of life -- it took more than a billion years just to establish an oxygen-based atmosphere. By 400 million years ago, there were already plants on land, and if our heroes had gone for a swim, they might have met one of these.
The King's Demons
On Doctor Who:
The Fifth Doctor, Degan, Nyssa, and Turlough arrive in England in 1215, where they encounter King John, busy harassing a minor lord in an attempt to extort taxes. But it can't be John; the king is in London taking the Crusader's Oath. This imposter king turns out to be a shape-shifting robot controlled by the Master, who intends to disrupt history by triggering a revolt against King John, preventing the Magna Carta from being signed.
The Doctor outlines the Master's plan
Actually, the Doctor has it pretty much backwards, and so does the Master -- it was the baron's revolt that forced King John to sign the Magna Carta. Only when it became apparent that he could not suppress the revolt with force of arms alone did King John consent to sign the decree, and he promptly renounced it once the barons left, plunging England into the First Baron's War. What's more, King John did end up dying during the war, of dysentery, an event which may actually have helped the Magna Carta; William Marshal, appointed protector of the nine-year-old King Henry III, used it as the basis of the new government in 1217. So rather than a baronial revolt preventing the Magna Carta, a baronial revolt was instrumental to its creation.
14th century copy of the Magna Carta
The Mark of the Rani
On Doctor Who:
The Sixth Doctor and Peri arrive in 1820s Killingworth, an English mining town, where previously gentle men have been turning into thugs embarking on Luddite riots. They meet the inventor George Stephenson, who is plotting a meeting of engineering geniuses, and who is working on a steam engine that he says could revolutionize transportation. The Doctor slyly tells him that his invention "will take off like a rocket," referencing an actual engine built by Stephenson in 1829.
The Doctor and Peri arrive in Killingworth
The real Stephenson probably would not have been keen to invite a group of engineering geniuses to a conference in the 1820s; in the 1810s, he'd been embroiled in a bitter intellectual property dispute because the intelligentsia didn't believe an uneducated man like him could have actually invented a safety lamp for miners. He understandably resented the attitude. And Stephenson didn't need to be told that steam power was the future; his first operational steam locomotive had already gone into service in 1814. While Stephenson indeed would go on to build the Rocket in 1829, it was important for a different reason: it won a speed race, and thereby the contract to build engines for the Liverpool and Manchester Railway, helping establish Stephenson's railway specifications as standards for the future.