What is the ruling on one who prayed in a direction other than the qiblah and then learned of it?

Question:
A group of people prayed the 'Isha' prayer in a direction other than the qiblah due to their own mistake, and they realized this after the time for the prayer had ended. Do they have to repeat it?

Answer:
If the deviation was slight, it is excused. If the deviation was significant, they must repeat the prayer.
Q: What if they deviated during the prayer and then corrected their direction?
A: If it was slight and they corrected it, that is sufficient.