Continuity mistake: The woman in the wheelchair that Dr. Cox claims is dead is wearing glasses in some shots but not in others.
Continuity mistake: When Elliot and J.D are going up the stairs and J.D asks if they are racing, Elliot has a watch on her left hand, then in the next shot when they are racing, the watch is gone and doesn't reappear.
Continuity mistake: Right at the end, the shot shows Carla walking towards JD with a security guard in the background, the shot cuts to behind JD and suddenly the security guard has moved forward in position dramatically.
Continuity mistake: Dr. Cox's stethoscope is hanging down more on his left side, but when he walks around to J.D. it is now hanging evenly around his neck. (00:21:40)
Continuity mistake: When JD is in the lift (elevator) with all the people and asks his patient if his gas is bad for the other people, the woman on the right has her arms crossed then in the next shot she has a single hand on her chest.
Answer: No, it was a fake, they used a stamp.
It is real.