[jahewson]

Fun fact, factoids are always false.

[ravenstine]

Necessarily? I'd assume a factoid has the potential to be either true or false.

[hhmc]

By some original definition of the word they are necessarily false. Usage seems to have shifted to ‘small fact’ though

[KennyFromIT]

The common misunderstanding of the word `factoid` to mean "a small fact" is itself a factoid.

[kjeetgill]

Oxford English Dictionary (via Google) gives:

Factoid

- a brief or trivial item of news or information - an assumption or speculation that is reported and repeated so often that it becomes accepted as fact

So both uses are reasonable?