Sometimes we see a mask is used by an actor of a film by which he drastically changes his face. I was under the impression that only after plastic surgery one can change his face. I stumbled upon this question while watching Don2. Here it is shown Shahrukh Khan changes his face drastically by using such mask to Hrithik Roshans face. I believe such mask does not exist because from IMDB I found Hrithik had a special appearance(I believe only for the face changing scene) in that movie. I am posting the screenshots to make you guys more clear about which mask I am talking about. Here Don i.e. Shahrukh Khan opens the mask:
Opening the mask
SRK showing his face
I remember similar masks were shown in MI 2 and 3. So how is this scenes done if the mask is not real?