If the Imaam makes a mistake in recitation, should the follower correct him? If he did not correct him but waited until after the prayer then corrected him, would this be right?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.

If the Imaam stopped or made a mistake in recitation, it is permissible for the one led in prayer to remind him and correct him. The proof is that Ibn ‘Umar, may Allaah Be Pleased with them, narrated that the Prophet, sallallaahu ‘alayhi wa sallam, made a mistake while reciting in one of the prayers. When he finished, he said to Ubayy, may Allaah Be Pleased with him: "Did you pray with us?" He replied: "Yes". He said: "Why did you not correct me?" [Abu Daawood, Ibn Hibbaan in his Saheeh and Al-Haakim]

Anas, may Allaah Be Pleased with him, said: "We used to remind the Imaams at the time of the Prophet, sallallaahu ‘alayhi wa sallam." [Al-Haakim]

Al-Haafith Ibn Hajar said that it was authentically narrated that ‘Abdur-Rahmaan As-Sulami said: ‘Ali said: If you felt the Imaam's  need to be corrected or reminded, then do (correct or remind him).

If the mistake is in Al-Faatihah by dropping one or two verses, the prayer is invalid till one recites the overlooked portion because the Prophet, sallallaahu ‘alayhi wa sallam, said: "Whoever does not recite Al-Faatihah, his prayer is invalid." [Al-Bukhari and Muslim on the authority of ‘Ubaadah ibn As-Saamit, may Allaah Be Pleased with him[

If he overlooked verses in recitation of chapters other than Al-Faatihah, the prayer is valid. The same applies if a mistake is made in the recitation in a way that changes the meaning but in a verse other than Al-Faatihah according to the preponderant opinion. If the mistake in Al-Faatihah changes the meaning, the prayer is considered invalid if he does not return to correct his mistake. It should be noted that no one should be an Imaam except someone who is skilful at recitation, and no one except him should be an Imaam when he is present.

Allaah Knows best.