Applicability: As the only book of the Bible about the future, the events depicted are really confusing and each have dozens of interpretations. Loads of fiction thus loves to call attention to elements of Revelation in their story, though usually just the most well known elements like Armageddon, the Antichrist (though there was no Antichrist in the book to begin with), and demons.
Broken Base: Is "The man named John," John the Apostle? There's been quite a debate over this.
Is the Book genuinely intended as a prophecy of the future, or is it a stealth Take That! at Emperor Nero? Note that "666" corresponds in Jewish numerology to "Neron Kaisar," the Greek form of his name. Especially considering that the book was specifically addressed to the leaders of churches that existed in John's day but no longer exist.
Other theories as to this "Nero" refer to the belief that Nero would arise again to wreak destruction on the world, or as a Roman à Clef for Domitian, whose self-deification and megalomania led others to draw parallels to Nero.
Common Knowledge: In canon, the white horseman is actually Conquest, but popular culture knows him as Pestilence. Perhaps because Conquest's schtick is already kind of covered by War.
It's likely that, due to Conquest's use of a bow, he was confused with Apollo, who also used a bow and used it to spread plague.
Ensemble Darkhorse: The four riders of the apocalypse. They have exactly one scene and have no mentioning in any other biblical book (apocryphal or not), and only one of them even gets a name (Death). They are amazingly popular in popular culture.
It's not called the Book of Revelations, as many think, it's The Book of Revelation. "Revelation" isn't in plural.
At no point is anybody by the name of Antichrist ever mentioned in this book. However, "Antichrist" is used to describe those who deny the Second Coming, i.e., anti-Christ.
The Rapture is also not in Revelation. It comes from Paul's letters to Timothy. note And the La Haye/Jenkins "Left Behind" conception of same is a belief that only was voiced by Evangelical preachers in North America starting in the mid 19th Century
"Armageddon" is not the name for the final battle between heaven and hell, but the Greek name for Mount Megiddo, a mountain in Israel where said battle takes place.