How should you correct the Imam during salah?
If a mistake has occurred, it is better to correct the Imam using the words ‘SubhanAllah.’ One can only say, ‘Allahu Akbar’, but it is better to use the words ‘SubhanAllah’.
And Allah ﷻ knows the best
Imam Ahmad Rida Khan رحمة الله تعالى عليه
Translation by Dr Musharraf Hussain Al-Azhari Translator of Majestic Quran, www.majesticquran.co.uk