I am on short visit to Dubai, and on my return flight I am planning to take the flight from Dubai(DXB) -> Mumbai(BOM) -> Rajkot(RAJ), and the operator will be Air India. My question is where the immigration process / passport stamping will be done ? At Mumbai Airport or At Rajkot Airport ?
Flights from Dubai to Rajkot on Air India are not 'direct', which means you will exit the plane in Mumbai as usual, enter India/get your passport stamp, and then proceed to wait for the departure of your second flight.
So the answer is that you will get your stamp in Mumbai.