When Danny describes to his mother why he lacks the skills to attract his crush Sam, she replies "Insignificant details." A nod to Love Actually (also written by Richard Curtis) where Sam responds similarly to his dad (played by Liam Neeson) "Tiny insignificant details."
Love actually, which is shown on the tv half way through, was also written by Richard Curtis.
In November 2019, it was announced that Locksmith Animation was developing That Christmas, an animated feature based on a series of Richard Curtis-penned children's books.
The lighthouse keeper Bill character is based upon Jacques Cousteau, a French diver and explorer known for his red hat as depicted in the movie.
That Christmas was originally expected to be released by Warner Bros Pictures under its Warner Animation Group banner, but in June 2022, Netflix acquired the distribution rights to the film with Netflix Animation taking over to produce. Unfortunately, Warner Bros. Pictures had no involvement with this film for unknown reasons.