A patient with a pacing wire has his pacemaker turned off while Dr Kutner stands by holding up defibrillator paddles. Turning off a pacemaker will make the heart slow down and stop, not fibrillate. Even if fibrillation was a danger, paddles would not be used - external defibrillation pads would be placed on the patient's chest and back well in advance to avoid wasting time.
House initially rules out the correct diagnosis of Lyme Disease because they cannot find the trademark rash from the tick bit. While the rash is a good way of confirming the diagnosis, one in 5 patients present without one, making its absence no good reason to rule out the condition.