Deliberate mistake: In one of the later episodes of season 2 Turk is seen being bored in surgery and checking the patient's wristwatch to see how long they have been operating. Patients are not allowed to wear jewelry or watches during surgery as there is a VERY high risk of infection and it might kill them.
Deliberate mistake: When the janitor pulls the plug on the phone, there would actually be nothing but dead air because the janitor just pulls the plug on the handset, not the whole phone. So they added a dial tone for comedic value. (00:22:20)
Deliberate mistake: When Carla shows Elliot what she looks like in the bedpan and Elliot says she looks like Alice Cooper, you can see her reflection in the bedpan. However the camera is to the side of Elliot's head, so if we can see her reflection, she wouldn't be able to.
My Ocardial Infarction - S4-E13
Deliberate mistake: In the scene where JD is practising emergencies with a corpse, you can noticeably see the corpse's chest moving up and down - it's breathing.
Answer: No, it was a fake, they used a stamp.
It is real.