Susan states that Janey is 19 in this episode. Daniela Denby-Ashe who plays Janey was actually 24, making her 5 years older than the character she plays.
Although her picture is featured in the opening credits, Siobhan Hayes does not appear in this episode.
This is one of three My Family Christmas specials to have the normal theme tune playing during the opening credits - the other two episodes to have this theme are Sixty Feet Under (the 2003 Christmas special) and Have an Unhappy Christmas (the 2008 Christmas special).