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 Evelyn Beatrice Hall (who wrote under the pseudonym S. G. Tallentyre) in her 1906 book The Friends of Voltaire to illustrate an attitude that Voltaire may have held. (source)

Acronyms (abbreviations pronounced as words, as opposed to initialisms, abbreviations pronounced as individual letters) were quite rare before the 20th century; the word "acronym" itself only dates from 1943. All stories about the origin of words (including "tip", "posh", "golf", and various four-letter words) that claim that a word is derived from an acronym several centuries old are false.

According to legend, St. Patrick drove all of the snakes out of Ireland. Actually, there were never any snakes in Ireland in the first place. (source)

Captain Kidd was hanged for murder, not piracy. He hit one of his seamen over the head with a bucket and killed him. The piracy charge was never proved.

Cleopatra was not Egyptian; she was of Macedonian descent.

The kilt is not Scottish in origin. It was a form of male attire in ancient times and originated in the Mediterranean area. Both Roman and Assyrian soldiers wore them.

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

In Mary Shelley's 1818 novel, Frankenstein was the name of the medical student who created the monster, not the name of the monster itself, which was not named.

"Willy-nilly" means "whether you want it or not"; it does not refer to being in a confused state. (source)

The word "devolve" is not the opposite of "evolve." Responsibility for something might devolve on you, but, for example, situations do not "devolve" into anarchy. (source)

The first aeroplane to fly nonstop across the Atlantic Ocean.

Charles Lindbergh was not the first person to fly across the Atlantic nonstop; he was just the first to do it alone. The first nonstop flight across the Atlantic occurred on June 14–15, 1919, when Captain John Alcock and Lieutenant Arthur Whitten-Brown co-piloted a Vickers-Vimy twin-engine plane from Newfoundland to Galway, Ireland. (source)

Mobile homes are not named for their portability. They are named after Mobile, Alabama.

In movies and television, people who are fatally shot or who otherwise die suddenly are usually depicted as falling backwards. However, someone who suddenly dies, from whatever cause, while standing, nearly always falls forward. Even if a person were struck by a bullet from the front, the bullet's momentum would usually be insufficient to overcome the tendency of a dying person to fall forwards. (source)

It is not true that there are no tides in inland bodies of water such as the Great Lakes. The same forces that produce ocean tides produce tides in all bodies of water, but in smaller bodies of water the tides are so slight that any changes are obscured by differences in water level resulting from other factors such as precipitation, discharge from rivers, atmospheric pressure and winds. For example, the tide at Lake Michigan rises and falls only a few inches. (source)