* AdaptationDisplacement: The film version has pretty much overshadowed the original stage play.
* BrokenBase: The war between fans of Julie Andrews and Audrey Hepburn is one of the hottest in musical theatre.
* CrowningMusicOfAwesome: "I Could Have Danced All Night" has gone down in the record books as one of the most beloved soprano solos in the history of musical theatre -- and with ''very'' good reason.
* EarWorm: [[http://youtu.be/7Ezy50aY6Bg I COULD HAVE DAAAAANNCCEEEED ALL NIIIIIGGHHT! I COULD HAVE DAAAAAANNCCEEED ALL NIIIIIIGHT! AND STIIIILLL HAVE BEEEEEEGGED FOR MOOOOOORRRREE!"]]
* FanPreferredCouple: Eliza and Henry, to Shaw's consternation.
* GeniusBonus: In the film, near the beginning we get a glimpse of Henry Higgins' notebook, which he's using to transcribe people's accents. It's unreadable... unless you understand [[http://en.wikipedia.org/wiki/Shavian the Shavian alphabet]], whose creation was funded by George Bernard Shaw.
* HoYay: Higgins and Pickering have quite a bit, particularly in "A Hymn to Him", where Higgins straight up asks "Why can't a woman be more like a man?".
* MemeticMutation: "The rain in Spain falls mainly on the plain."
** "I've grown accustomed to her face."
* RetroactiveRecognition: Eliza's potential suitor is Series/SherlockHolmes.
** When it was first made, Eliza came across as much more unacceptably uncouth to theatre-goers, and therefore just as bad as Henry, whereas it's getting more and more common to see Henry as a misogynistic, snobbish villain unfairly putting Eliza down. Basically, they're each supposed to be a JerkWithAHeartOfGold, but current values don't look favorably on characters like Higgins.
*** There's also an element of laissez-faire that won't be present to today's audience. Modern audiences sympathise with Eliza since her poverty and upbringing would naturally cause her to be rough in her speech and mannerisms, but older ones might be less sympathetic. To today's audience Henry also comes off as arrogant, buying Eliza for an entertaining game while she just wants to make a fair deal to rise above her station and pay for lessons, and he implies she should be grateful just because he was luckier in life than she was, and even implies that she's basically one of his belongings in one scene.
** Freddy's love-sickness and patient wait is stalking in today's terms, and while it would have been seen as romantic by all parties at the time, easily disturbs people nowadays.