Continuity mistake: Keifer initially grabs Ethan's neck with his right hand and pins him up against the wall with it, but for the rest of the scene he's using his left. (01:08:50)
Continuity mistake: When Angelina goes to the scene of the murder witnessed by Ethan, she is seen sitting on the footpath. At the start she has a pad on her left knee and a pen in her left hand. However as the scene progresses, it disappears and reappears several times. (00:23:35)
Visible crew/equipment: At the very beginning after the white van hits Matt, there is a crew member behind a hay stack. (00:05:50)
Answer: Yes, he must do this to truly feel like the different person he is trying to be. Also, so the police won't suspect anything if his traits don't match his identity.