The Shulchan Arukh (YD 240:2) rules that one is never allowed to contradict one's father in his presence, and that when it comes to one's rav (or one's father if he is a Torah scholar; YD 242:1-2), disagreeing with him is like disagreeing with the shekhinah itself. Formulations of a similar nature are found in a number of texts, and lead me to wonder: in the event that one's rav or one's father is leyning from the Torah and makes a mistake, is one always permitted to publicly correct him, or are there situations in which it is better to let him continue?
By way of an example, if he were to make a mistake in his leyning of Parshat Va'etchanan, mispronouncing one of the words in Devarim 6:4-9, should one correct him? Note that doing so would also indicate that he habitually mispronounces the words in his daily recitation of Shema, which may be tantamount to declaring publicly and in his presence that he has never fulfilled that particular mitzva.