During the reprise of "Thank You Very Much" at the end of the movie, the crowd sings and dances their way past the booth of the Punch and Judy man, and the camera stops to focus on him. Just to the left of his booth, the actors can be seen stopping and turning back as they are now "off-camera". The next shot after the Punch and Judy man, however, shows them continuing down the street.
After Scrooge wakes up to discover it is Christmas day, he slides down the banister in his home. The banister is very dusty, and when he first jumps off, one can see a glimpse of the four-inch wide line of dust/dirt down his night shirt. In the next scene, he walks into the street in his nightshirt, and there is no line of dust/dirt down his front.
While with the Ghost of Christmas Present, Scrooge peeks into a home, wiping the frost and condensation off the window. Setting aside the question of whether an incorporeal spirit could do this, frost and condensation collect on the warm side of a window, not on the cold side, where Scrooge is.
During the dance sequence at Fezziwig's warehouse only Fezziwig himself is actually dressed appropriately for the era that the memory would have taken place in. An 18 to 20 year old Scrooge would have been working there in the mid to late 1700s, yet nobody else at the dance is dressed in colonial attire.
Scrooge describes his nephew Harry as being "poor". Yet when he visits him with the Ghost of Christmas Present, Harry and his wife are living in a large, opulently furnished and decorated London townhouse. However, "poor" is not an absolute concept, but is a matter of degree. Just as the Cratchits might appear rich to someone who is homeless, Harry's wealth, to Scrooge, is minimal.
Just before The Ghost of Christmas Present and Scrooge fly through the window, the wires that are connected to Albert Finney can be seen.
The Ghost of Christmas Yet to Come's face is meant to be hidden in the shadow of his hood, but in the cemetery, the cloth covering Paddy Stone's face is visible in several shots.
The wires connected to Alec Guinness's harness and chain to give the effect of floating are often visible.
When Marley levitates into the air, in some shots, his wig is parted in the back and his neck can be seen: it is a normal, peachy flesh tone and has not been painted with the blueish-white ghostly makeup that his exposed parts have been.
In all the night street scenes, the shop windows are too brightly illuminated to be made with just candlelight or gas lanterns, which would have been the only sources at the time this story takes place. They are obviously electric lights, something only available far in the future.
After Scrooge repents, he wears a modern day Father Christmas suit. The famous red and white Father Christmas suit did not exist in its current form until about the 1900s.
Although the Ghost of Christmas Past takes Scrooge back to his childhood, all costumes in the flashbacks are of the mid-nineteenth century, when the action starts.
Dame Edith Evans, as the Ghost of Christmas Past, is seen wearing a large bustle. Bustles weren't invented until almost a generation later.
When Tiny Tim is first seen, he and his sister are looking into a toy store window. Looking closely at the bottom right corner of the screen as the camera zooms in on Tim, the shadow of the camera on a dolly can be seen.
This version incorporates a sequence set in hell not present in the original novella. In the sequence, Jacob Marley is the one to greet Scrooge and explain his eternal punishment to him. The earlier appearance of Marley's ghost establishes that, just as in the novella, he is not in a version of hell: rather, his punishment is to wander the Earth without rest, fettered, until the end of time.
During 'Thank You Very Much' Tom Jenkins is dancing on top of Scrooge's coffin. As it is rounding the corner, Tom bunts the character behind him off the coffin, then briefly holds out a hand to try and catch him.