Other mistake: When the power outage occurs, Daphne claims she can't cook the steaks, however, the cook top in the kitchen is gas. They have matches as shown by them lighting the hurricane lamps.
Factual error: There are many factors concerning Niles' post-operative state which are very inaccurate. After open heart surgery it takes at least three months for the chest bone to heal, Niles would not be able to drive a car for weeks, nor would he be able to lift or twist which he does on the show. Also, he doesn't sport a scar. Your chest bone begins very high up, just below your neck, his scar should have been visible on numerous occasions.