Julius Caesar did not coin the phrase "The die is cast", which he remarked before crossing the Rubicon. According to Plutarch, the phrase was common even in Caesar's day, having been used by the Greek dramatist Menander. Furthermore, there is some doubt whether Caesar even said this phrase, as he does not mention using this phrase in his writings. (source)

Canute (also spelled Knut), King of England (1016–1035) and of Denmark and Norway for most of that time, is well-known for having ordered the tide to retreat. However, he did not do so because he believed that he could actually stop it. He did it to demonstrate to sycophants that he was not omnipotent.

The Hundred Years' War actually lasted 116 years, from 1337 to 1453. (source)

It is not true that the early Chinese used gunpowder only for fireworks. They had forms of guns (invented in 1288), bombs, grenades, rockets, landmines, flamethrowers, small cannons, and other weapons.

Few witches were burned during the Middle Ages; most witch-burnings happened in later centuries.

In the fifteenth century, Prince Henry the Navigator dispatched his sea captains on voyages to explore the African coast. One of Henry's hopes was that his men would discover the rich Christian kingdom of "Prester John", which was supposedly cut off from the rest of Christendom due to the Islamic conquest. Eventually, after Henry's death, the Portuguese rounded the Cape of Good Hope and sailed the east coast of Africa, only to find that Prester John's kingdom did not really exist. While they found a Christian kingdom in Ethiopia, it was dismissed as being that of Prester John due to its poverty. (source)

The Emancipation Proclamation freed very few slaves immediately. Issued by Abraham Lincoln on January 1, 1863, the proclamation applied only to slaves in areas controlled by the rebel Confederate government, where Lincoln had no authority to enforce it. (source)

In 1903, Albert Michelson, one of the 19^th century's top physicists, commented "The more important fundamental laws and facts of physical science have all been discovered, and these are so firmly established that the possibility of their ever being supplemented in consequence of new discoveries is exceedingly remote". Two years later, Einstein published his revolutionary Theory of Special Relativity.

As late as 1820, the universe was thought by European scientists to be 6,000 years old. It is now thought to be about 13,700,000,000 years old. (source)

The Eastern side of the Panama Canal connects to the Atlantic Ocean and the Western side of the canal to the Pacific, not the other way around. (source)

Ostriches never stick their heads in sand. (source)

The White House did not obtain its name because it was whitewashed after being burned by the British in the War of 1812. The building was already known as the "White House" before the sack of Washington in 1814. (source)

In 1985, NASA estimated the probability of a space shuttle accident to be 1 in 100,000. However, on the 25^th shuttle launch on January 28, 1986, Challenger exploded after take-off, killing all seven astronauts aboard; on February 1, 2003, the 113^rd mission, Columbia exploded on re-entry, again with the loss of all seven astronauts. Other groups had earlier estimated the probability of failure as being closer to 1 in 100, a probability that now seems more reasonable.

Heart attacks generally do not kill people. It is the complications from heart attacks, such as scarring of the heart tissues, that kill people. (source)

The Sahara Desert, the world's largest desert, is not the largest sand desert. Only 15% of the Sahara is sand dunes, while over 70% consists of stone desert. The largest sand desert is the Great Arabian Desert, or Rub-al-Khali, in the Arabian Peninsula. (source)

Arabic numerals are not Arabic. While Europe obtained this system from the Arabs, the Arabs in turn obtained this system from the Hindus around the middle of the eighth century. The Hindu writer Aryabhata first described the new system in the year 499. The invention of the sign for zero made arithmetic computation much easier. In contrast, calculation was more awkward in the Roman numeral system. (source)

It is untrue that carrots are good for your eyes. This belief started in World War II, when the British began using airborne radar, allowing them to find German bombers at night. In order to mislead the Germans, a rumour was spread indicating that John Cunningham, the Royal Air Force's most successful night fighter pilot, had developed phenomenal night sight by eating carrots in large quantities.

Abner Doubleday did not invent the game of baseball. The story of his invention of the game was created many years later based on hearsay and credited to Doubleday due to his fame as a general in the Civil War. Alexander Cartwright, a New York City bank clerk who devised several changes to the American form of rounders in 1844, is probably the best candidate for the inventor of baseball. (source)

The Jerusalem artichoke is neither from Jerusalem nor an artichoke; it belongs to the sunflower family. The Italians called it girasole articciocco, "sunflower artichoke". Over the years girasole became "Jerusalem". (source)

There was no grass during the time of the dinosaurs. Grass evolved from bamboo-like plants only 24 million years ago.

Napoleon was not particularly short. He was 5 feet 6½ inches tall, which was a typical height at the time. This height is equal to 5 feet 2 inches in old French feet (pieds du roi), which led to confusion as to his true height. (source)

There is no silver in German silver. It consists of copper, zinc, and nickel. (source)

It isn't true that many of the strange, outdated laws that are still on the books in various jurisdictions are never enforced. In 1999, after falling out of his canoe on the Rifle River in Michigan, a 25-year-old man was convicted for violating an 1897 law prohibiting cursing in front of women and children, and sentenced to four days work in a child-care program plus a $75 fine. However, the law was struck down by the Michigan Court of Appeals in 2002 and the conviction thrown out. (source)

The phrase "Beam me up, Scotty" was never uttered during an episode of Star Trek. (source)

Fortune cookies are American, not Chinese. They were invented by George Jung, a Chinese immigrant to the United States, in 1918. (source)

The original boomerangs, used by Australian aboriginals, did not return. They were used for hunting, where returning would be a disadvantage. (source)

The primary aim of the Inquisition, which operated between the twelfth and fifteenth centuries, was the conversion of heretics, not their destruction. A person would only be considered a heretic if they persisted in their views after three detailed cautions. Even then, that did not always lead to being burned at the stake or otherwise executed; there were Inquisitors that did not pass a single death sentence. (source)

The Wright Brothers did not fly the first manned airplane. On August 14^th, 1901, a man named Gustav Albin Whitehead (born Weisskopf), flew a plane around half a mile (800 metres). However, without documentation such as photographs to support his claim, there was significant scepticism about his claim and it was not taken seriously. (source)

Lead pencils contain no lead. Lead pencil is as much a misnomer as it would be to call a horse a cow. Red lead is an oxide of lead, and white lead is a carbonate of lead, but the black lead used in pencils is neither a metal nor a compound of metal. It is plumbago or graphite, one of the forms of carbon. (source)

Voltaire never said the quotation for which he is well known— "I disapprove of what you say, but I will defend to the death your right to say it." It was created by Beatrice Hall (who wrote under the pseudonym S. G. Tallentyre) in a 1907 book as an example of something Voltaire might have said. (source)