At least three or four times since Reagan's death, most recently tonight during radio reporting of the part of the Republican convention in which a commemorative video was shown, I have heard reporters and commentators giving misty-eyed reminiscences about hearing President Reagan say, "Mr Gorbachev, tear this wall down." He said no such thing, not ever. People sometimes say linguists fuss over trivia, but I can't believe anyone could see this point as trivial.

It's so strange that people should misremember, for two reasons. First, the correct original version still phonetically rings in my ears, unforgettably, and I would have thought that would be true for anyone who heard it (which would include even a 30-year-old junior reporter: the speech was in 1987); and second, the way he put it — synonymous, but with with very slightly different syntax — is so much more compelling. The rhythm is better; the parallel with the preceding sentence ("Mr. Gorbachev, open this gate!") is better; and (let me get technical for just a second) the crucial direct object is positioned as last constituent in the verb phrase, not followed by the anticlimax of a particle that belongs with the verb, so the nuclear stress coincides perfectly with the final monosyllable which delivers the pragmatic punch, the key piece of new information conveyed by the final noun. Syntax, prosody and pragmatics in perfect harmony. What President Reagan said, very deliberately — and they say it was audible over on the other side in East Berlin — was: "Mr Gorbachev, tear down this wall!"
— Geoffrey K. Pullum