James Stewart approached the scene where Mr. Kreuger talks to the infant Jesus very seriously. Before filming this scene, he told the producer Michael McLean, "I've got only one of these in me. Everyone who doesn't need to be here, get them out. Tell them I want this to go well. I can do other takes, but this will be the right one. There will only be one." After the scene was finished, McLean asked the cameraman, "Did you get it?" "I hope so," was the reply, "because I was crying."
Stewart said that he had a lifelong dream of leading the Mormon Tabernacle Choir which he fulfilled during filming. He also accepted the role because he believed it would promote the true meaning of Christmas. He said that Christmas "has come to be connected with Santa Claus, gifts, lights, decorations, trees," .. "We may be guilty of forgetting that Christmas is really the celebration of the birth of Jesus Christ."
The scene where the Mormon Tabernacle Choir starts clapping and gives Willy Krueger a standing ovation was the actual reaction of the Choir to James Stewart's directing. It was a total surprise and completely unscripted.
In the digitally remastered 25th anniversary edition DVD released in November 2005, the Mormon Tabernacle Choir parts (including the "spontaneous" applause) have been re-recorded because the original recordings were not adequate. The Salt Lake Tabernacle (the Choir's home) is undergoing extensive seismic upgrades, so the recordings were done in the new 21,000-seat LDS Conference Center across the street. A few current Choir members actually participated in the original filming.
Michael McLean, who wrote the original story, had never produced a movie before. To appear more professional, he took the script to Stewart's agent pretending to be a delivery man. He later returned as himself to discuss the project.