This movie is based on the book "The Best Christmas Pageant Ever" by Barbara Robinson, published in 1972.
Dallas Jenkins wrote personal messages to Judy Greer, Pete Holmes, and Lauren Graham, explaining what he admired about them, why he thought they were perfect for the part, and kindly asked that they consider it. All three actors said yes.
Just prior to the end credits, what became of each of the Herdman kids as adults is shown.