Characters getting a swap: FBI Special Agent Sean Archer (John Travolta) and criminal Castor Troy (Nicholas Cage)
Type of body-swap: Face-swap only. Archer undergoes a face transplant surgery so he can assume Castor’s identity and get info on a bomb the terrorist has hidden.
Lesson learned by body-swapping: If you’re a doctor swapping the faces of an FBI agent and a comatose dangerous criminal, don’t let the criminal wake up. That mistake will cost you your life.