The ethereal glow effect on the Ghost of Christmas Past seems to turn on and off arbitrarily.
While visiting Bob Cratchit's family home, Scrooge and the Ghost of Christmas Present approach the front door but are then seen entering the kitchen area from a side stairway. Bob and Tiny Tim come through the same door a couple of minutes later and enter directly into the kitchen area.
There is no entry in an 1843 Register of Death that would require the signature of Ebenezer Scrooge. There is no space for a witness or next of kin and all information would have been entered by a registrar or clergyman making the opening scene factually inaccurate. In truth, Stewart, who was merely following the opening lines of the original book, was not to blame for this. The fault lies with Charles Dickens who wrote 'The register of his burial was signed by the clerk, the undertaker and the chief mourner' and this may be traced to lack of knowledge on behalf of the author who, aside from signing his own marriage register (a much more detailed pro forma) would have not have come into contact with the registers which were normally kept locked away in the parish chest.
In the snow scenes outside Scrooge's old school, swifts are heard but these migratory birds arrive in May and leave in August.
During the dancing at Fezziwig's, the supposed brick floor can be seen bouncing slightly beneath the footfalls of the dancers, revealing it to be a false flooring.
When the Ghost of Christmas Past is talking to Scrooge near the end of their visit to Fezziwig's, the glow effect for the ghost has been layered over the railing the ghost leans on as well as the ghost himself so that a portion of the rail (matching the ghost's silhouette) glows as well.
When Scrooge is back visiting his apprenticeship Christmas party, a sideways view of the musician playing the large serpentine wind instrument shows a large black mouthpiece hovering in front of his mouth, whereas moments earlier, from the front, it was a real gray trumpet-like mouthpiece actually attached to the instrument.
At the end of Scrooge's visit to the Cratchit's during Christmas Present, Tiny Tim starts singing "Silent Night" which is then taken up by others in various scenes. Originally a German-language hymn written in Austria, it was not translated into English until 1863, a full 20 years after Dickens wrote "A Christmas Carol".
Marley died in 1836, and the story takes place seven Christmas Eves later in 1843. The caroler at Scrooge's door sings Good King Wenceslas, but the lyrics for that song were not written until 1853.
While Scrooge and the Ghost of Christmas Past are visiting Fezziwig's old shop, Mrs. Fezziwig tells Mr. Fezziwig to "hold your horses." The first documented use of the idiom to "hold your horses," meaning to exhibit patience, was in America in 1843. The "present" sections of this story take place in 1843, in England, putting the Fezziwig scene several decades prior, and on the other side of the world, from when and where the phrase would first come into use.
When Marley informs Scrooge of the spirit visit times, he says to expect them at whichever time "the next night", implying 3 separate nights. Since it is Christmas Eve and the story concludes on Christmas Day, it was supposed to be 3 visits in during the overnight between 12/24 and 12/25, or just one night.