As the Tishell's eat their meal, the flame on the candle in the centre of the table is either blowing strongly sideways (in shots from the left) or perfectly still (in the shots from the right).
In addition to erroneously administering insulin for a case of very low blood sugar, which wouldn't have been the case for a newly diagnosed case of juvenile onset diabetes anyway, Doctor Ellingham reported that he gave insulin subcutaneously. In fact the injection was intramuscular.
A doctor would never inject insulin into a patient with a glucose level of 29. That is an extremely low glucose level. The proper thing to do is administer glucose either orally or intravenously. Insulin would lower the level even more, endangering the patient.
At one point, just before treating Clive Tishell, Doc Martin tells Sally to stop doing CPR as his heart has stopped. He then uses a defibrillator on Clive. Given that CPR is appropriate for a stopped heart and that a defibrillator will not start a stopped heart, it appears that Doc Martin meant to say that his heart hadn't stopped.