In the outdoor scene where Ebenezer and Belle break their engagement, they rise from the bench and walk a ways to their right. After Belle leaves, and Ebenezer is shown standing alone, he is back up the path on the other side of the bench.
The Ghost of Christmas Future takes Scrooge to the cemetery near the end of the movie. At the beginning of this scene, when Scrooge asks why they are here, you can see a rope at the bottom of the screen that pulls the Ghost across the graveyard to simulate it floating across on air.
The dome of St Paul's Cathedral is visible just a few streets away from the Cratchits' house. Near the end of the film, however, Scrooge tells the poulterer to deliver a goose to the Cratchits' house in Camden Town (as named in the book) - over four miles away from St Paul's.
The string holding up the Spirit of Christmas Past's snuffer is briefly visible when she removes her hand from above it in the first scene with Scrooge. The snuffer shakes and wobbles perceptibly (as the string is slightly moved) throughout the scene.