Iwan Rheon, a songwriter as well as an actor, wrote the "Christmas number one" song with composer Guy Chambers.
Iwan Rheon, an accomplished singer-songwriter, does his own singing and guitar-playing in the film.
The film was rewritten to make Nina half-German to accommodate Helena Zengel after she expressed an interest in appearing.
First movie role for Alfie Boe, who flew back from a concert residency in Las Vegas to appear in the film.
The film was shot in Covid conditions over the hot summer of 2021, with the cast having to wear winter clothes in the heat to maintain the illusion of winter. It was greenlit in March for a delivery date of end of October, an unusually tight schedule for a movie.