In the scene where Sam has just died, and he is now at the hospital, he sits down in a chair next to an old man who is also a ghost. He talks to the other man for a few minutes, and then the man disappears. Sam is so shocked that he jumps up from the chair in search of this other man, but if you watch when he jumps out of the chair, he grabs the arm rest with his right hand. In fact you can even hear his hand slap against the arm rest because he is in such a hurry.