In one scene, Lady Bagshaw and Mr. Carson are mistaken for a married couple. Dame Imelda Staunton and Jim Carter have been married in real life since 1983.
The fact that the movie that was made at Downton helped to fund a new roof is based on real life. The real Highclere Castle was not in good shape, but because of Downton Abbey (2010) being shot at it, the owners were able to fund a new roof.
In interviews, Sophie McShera (Daisy) said that she was a bit jealous of her costars who got to go to France. She said that Jim Carter (Mr. Carson) would send texts to her with pictures from the south of France.
The location used for Tom and Lucy's wedding is Belchamp Hall in Essex, with the adjacent church of St. Mary the Virgin, Belchamp Walter hosting the ceremony. The bells heard as they leave the church are not the bells in the tower and were dubbed on for the soundtrack, as the church's eight bells (dating between 1712 and 1891) are unsafe to ring as of 2022.
Laura Carmichael was pregnant while filming some of the movie. She gave birth to a baby boy in March 2021 with Michael Fox who plays Andy.