The word "humbug" is misunderstood by many people, which is a pity since the word provides a key insight into Scrooge's hatred of Christmas. The word "humbug" describes deceitful efforts to fool people by pretending to a fake loftiness or false sincerity. So when Scrooge calls Christmas a humbug, he is claiming that people only pretend to charity and kindness in a scoundrel effort to delude him, each other, and themselves. In Scrooge's eyes, he is the one man honest enough to admit that no one really cares about anyone else, so for him, every wish for a Merry Christmas is one more deceitful effort to fool him and take advantage of him. This is a man who has turned to profit because he honestly believes everyone else will someday betray him or abandon him the moment he trusts them.
This is, perhaps, the only version of ACC in which Scrooge wears dress-slacks, a dress-shirt and a vest (with an Alistair Cooke-type smoking jacket)...instead of merely his nightgown, slippers and cap. (Rumor has it that George C. Scott openly reeled at the very thought of portraying Scrooge under such conditions...especially in mid-winter England.) In the book Scrooge is wearing his shirt, pants, vest, a dressing gown and slippers. Scott's clothing is very close to the book.
When Scrooge comments on the existence of prisons and work houses he says "I was afraid from what you said something had stopped them in full force" which does not make any sense except that it rhymes with the actual line from the book which is: "... stopped them in their useful course".