The pillows on Scrooge's bed disappear when he runs to the window to see who is singing "Deck The Halls".
When Bugs Bunny (disguised as a ghost) appears to Scrooge, he has his arms up and his eyes wide. In the next shot, (close-up) his arms are outwards and his eyes are angry.
The door is closed when Scrooge asks the ghost, "Down there?"
In the next shot, the door is open.
When Bugs puts the piece of burning coal into the stove for Porky, the stove has an exhaust pipe and chimney. When Scrooge/Sam goes to get it, the exhaust pipe and chimney are gone.
When Bugs Bunny quietly sneaks a piece of coal into Crachit's workroom, Scrooge is counting his money and reaches 5,887. Bugs Bunny leaves while Scrooge counts up to 5,892. Then Scrooge's cat notices a piece of coal missing from the fire. When he makes Scrooge lose count, Scrooge had just counted 5,889.
Bugs Bunny (disguised as a ghost) puts his arms up when he tells Scrooge that he's taking him to see the man in the red suit. Bugs' shadow, however, does not put its arms up.
After Scrooge/Sam kicks Bugs out, Bugs comments that, "Somebody ought to teach that little humbug some Christmas spirit!" Scrooge/Sam goes back to counting coins, and counts from 5885 to 5890 (6 coins) - but puts 10 coins in the box.