When Dudley sits down to have dinner with the Bishop and his wife, the Bishop has a stalk of celery in his left suit pocket. He removes it from the pocket as he sits down. In the next shot it is back in the same pocket and he takes it out again.
Right after the planning meeting near the beginning of the film, the Bishop and Julia are having a discussion. Around her neck is a bow with two strings hanging down, the right one just a little longer than the left. When they sit down at the dinner table immediately following, the right string is now way longer.
Much of the movie takes place in the drawing room. Pay attention to the small table in the background in front of the large window as the objects on the table change their position from scene to scene.
Whilst Dudley is telling the story of David to Debby, Miss Cassaway comes out and stands in front of the library door. By the time Dudley finishes the story, she's standing to the right of the door and then in front of the door again.
In the opening scene, the caboose is in the middle of the train in the window; the caboose should be at the end of the train.
Obvious stunt double when Dudley shows Julia how he can spin on the ice; he appears shorter and seems to be wearing dark-rimmed glasses.
On the first morning, as Dudley is walking back into the study to organize the index cards, there is an editing error. You'll see a very brief exterior shot. It's too quick to see what it is in real-time, but if you pause it, you'll see that it's from the scene of the previous evening with Dudley and the Professor standing in front of the old church building. (Error was removed from later prints.)
In the final scene when the bishop is giving his Christmas sermon, the hymn board has three hymns listed that are scattered through the hymn book, but Christmas hymns would all be within a few numbers of each other.
During the kid's snowball fight, a snowball hits a kid and it bounces into the air. Obviously, not a real snowball.
In several shots throughout the movie, the dog trainer's shadow can be seen. When Dudley pushes Julia's chair in, at Henry's back a shadow moves, and the dog gets up and walks over to Dudley.
When Dudley is "summoning" the boys to the choir rehearsal, two boys enter from over his right shoulder through a door where an arm can be seen holding it open for them.
At the end of the movie, as the angel is talking with the bishop, it appears the angel is being urgently called back to heaven, as twice Cary Grant looks upward and says something along the lines of "Just a minute." However, the very end of the movie shows the angel outside the church listening to the bishop give his homily.
Dudley states that Wutheridge's coin was struck by Julius Caesar to pay for Cleopatra's hotel bill when she visited Rome. Dudley would know that Cleopatra stayed at Caesar's villa as his guest the two times she was in Rome.
Mrs. Broughman asks Mr. Maggenti to deliver the Christmas tree late on Christmas Eve so as to surprise her daughter. Maggenti confirms he will deliver the tree after "the little bambino" goes to bed. Bambino is an Italian endearment term for a baby boy, not a baby girl. It is okay to use bambino as a general term when the gender is unknown or unspecified, however Maggenti clearly heard that the child in question is a girl. Instead he should have used the term "bambina".
After Dudley joins Julia in the park, they go to lunch at Michel's and then pay a visit to the Professor, but later when they return home and Julia tells the Bishop about their day, she says they went to visit the Professor and then went to Michel's.
When Dudley first composes the Christmas sermon he mentions the gift of a tie before a book, but when the bishop gives the sermon, he reverses the order and mentions the book before the tie.