Dickens' family did, indeed, keep a pet raven, which died unexpectedly while the family were away. Dickens told this story to another author -- Edgar Allan Poe -- who was then inspired to write a poem about a raven.
At 87 years old Christopher Plummer is the oldest actor to ever play Scrooge. In fact Scrooge is apparently elderly in the book while in the previous films Scrooge is played by various middle aged actors.
The booklet Dickens borrows from Tara the maid, "Varney The Vampire or The Feast of Blood", is a real gothic novel written between 1845 and 1846 by James Malcolm Rymer and Thomas Preskett Press. The novel was written in a format of monthly weekly deliveries, one penny a piece pamphlets, usually containing cheap horror literature, so each was commonly known as a "penny dreadful". This can be a nod to the fact that the movie was filmed in the same sound stages as the Showtime TV series 'Penny Dreadful' (2014).
A majority of this film's cast are trained Shakespearean actors, and have appeared in numerous stage, television and film productions of the bard's work. Coincidentally, Dickens himself was a fan of Shakespeare, and even appeared in amateur productions of his plays for charity. In the first few pages of A Christmas Carol, Dickens also references Shakespeare's tragedy Hamlet, comparing Jacob Marley's ghost in his novella to the ghost of Hamlet's father.
Miriam Margolyes has had a long history with the life and works of Charles Dickens. She has appeared in two adaptations of the author's most famous works (Oliver Twist (1985) and Little Dorrit (1987)), appeared in a parody of A Christmas Carol (the TV short Blackadder's Christmas Carol (1988)), presented the documentaries Dickens in America (2005) and The First Fagin (2012), and portrayed the older version of Dickens' wife Catherine in the three part docudrama Dickens (2002).
Simon Callow has previously appeared in the miniseries David Copperfield (1986), which was adapted from Dickens' autobiographical novel of the same name. Callow appeared as the eccentric debtor Wilkins Micawber, whom Dickens based on his own father, John Dickens.
Bill Paterson and Miriam Margolyes have both appeared in adaptations of Little Dorrit, one of Charles Dickens' later works. Paterson as Mr. Meagles appeared in the 2008 BBC miniseries adaptation, while Margolyes as Flora Finching appeared in the 1987 adaptation.
The idea of characters from a work of fiction in the process of being written appearing as real persons advising the author as he is writing the story was used in "The Wonderful World of the Brothers Grimm" (1962).
Simon Callow and Ian McNeise previously worked together on Ace Ventura: When Nature Calls, which also stared Jim Carrey as Ace Ventura. Jim Carrey went on to star in his own adaptation of Charles Dickens' A Christmas Carol.
Cast members Miriam Margolyes, Ian McNeice, Ger Ryan and Jonathan Pryce have previously appeared in adaptations of Oliver Twist, another popular novel that Charles Dickens wrote. Margolyes portrayed Mrs. Corney in the 1985 miniseries produced by the BBC, as well as narrated the 2012 documentary The First Fagin, about the creation of the novel's villian, Fagin. McNeice appeared in the 2005 film adaptation as a workhouse board member. Ger Ryan appeared in the 1999 miniseries adaptation as Mrs. Sorrowberry, the undertaker's wife. And Pryce played the role of Fagin during the 1994 West End revival of Lionel Bart's Oliver!, and even appeared on the show's cast recording.
Cast member Ian McNeice has appeared in several other adaptations of Charles Dickens' work: The Life and Adventures of Nicholas Nickleby (1982); David Copperfield (1999); A Christmas Carol (1999); Oliver Twist (2005); and The Mystery of Edwin Drood (2012).
Donald Sumpter (who portrays Jacob Marley in the film) has appeared in two other adaptations of a Charles Dickens story: Great Expectations (1999) and The Life and Adventures of Nicholas Nickleby (2001).
Miriam Margolyes & Ian McNeice appeared together previously in the television series, "Doc Martin". McNeice is a regular cast member on the program; Margolyes guest-starred as a poison victim tended to by the titular doctor.