correcting a mistake while lead by an Imam

Salaams! How does one correct a mistake during fard Salaat with Jamaat? Eg. sitting in tashahood instead of rising in qiyam whilst in the first rakaat. Please verify.

Wa Alaikum As Salaam,
If it is the Imaam who has made a mistake in the Salaat, then he must accept the correction given by the Muqtadi (when he hears Allahu Akbar or Subhaanallah from the Muqtadi). He will then go to the correct position and then make the two Sajdah of forgetfulness at the end of the Salaat.
If it is the Muqtadi who makes the mistake while performing Salaat behind the Imaam, then he would simply continue to follow the Imam in all his actions. The Muqtadi is not allowed to make the 2 extra Sajda of forgetfulness (on his own without his Imaam).
If he does this, then he will be opposing the Imam which is not allowed.
And Allah knows best,
Mufti Waseem Khan