The nun waking up the other nuns by knocking on the door of their cells says "Deus gratias", and the nuns within reply in the same way. This is a traditional greeting in the Benedictine order (the location is a former Benedictine abbey), but the greeting should be "Deo gratias": to God, thanks. "Deus gratias" is very poor, ungrammatical Latin.
The nuns often refer to their building as "the abbey". In fact, the location is an abbey, but the house of an order of Sisters is usually called a convent.
At about 1:19:00, Talia tells Faith to meet her in the "firmary" - but she really must mean the INFIRMARY. It's a wonder this wasn't caught and re-shot.
Sister Joy, as Mother Superior, tells Sister Talia to kill the person responsible for the murders which have occurred. Talia resists, but Joy says she will personally forgive whatever she does in confession. Apart from being a command that no religious would ever take seriously, only a priest can administer the sacrament of confession.