Mickey Rooney, who plays Mr. Dominicus, and Jan Rooney, who plays Sister Bernadette, were real life husband and wife.
Angelarum Dominicus (Mickey Rooney's character name) translates from Latin as "The Lord of Angels". Merry Christmas.
It may be a coincidence, but Henry Gibson plays a character named Henry Beemus and Burgess Meredith played a very similar character named Henry Bemis in The Twilight Zone's "Time Enough at Last".