Misspeaking is a term to describe when a person will mispronounce a word, leave it out accidentally, get the word order wrong, or make other mistakes. The general practice is to correct it right away if it's significant, although in some spheres of communication it's better to let it alone - particularly in broadcasting when the mistake is minor.
Liberals like to make a big deal out of tiny errors in speeches by Republican politicians. The most notorious case was noted by Ann Coulter, regarding a line that President Ronald Reagan read in a speech correctly 9 times out of 10. The one time he got it wrong, he interrupted his speech to correct himself. Yet the liberal press magnified that one speaking error, distorting it into a misstatement or even a misquotation. They accused Reagan of not knowing the correct quote, (deliberately?) ignoring the fact that he immediately recognized his mispronunciation - something he could not have done if he didn't know the quote by heart.