How is an animal slaughtered, and does a mistake in the method of slaughter prevent its consumption?

Slaughter has obligations and Sunnah acts. Its obligations are that the slaughterer be a Muslim or a person of the Book, sane and discerning, that the slaughtering tool be sharp, that the windpipe and esophagus be cut to drain the blood, and that Allah's name be mentioned at the time of slaughter, though the mention is waived if forgotten. Among its Sunnah acts are saying 'Allahu Akbar' along with 'Bismillah', facing the slaughtered animal towards the Qibla, expediting the slaughter, and cutting all of the windpipe, esophagus, and jugular veins. If a condition for the validity of the slaughter is violated, the slaughtered animal is not lawful. However, if a Sunnah act is omitted, the slaughtered animal remains lawful.