Factual error: The first shot of the calendar shows two days numbered as 20 and March ending on the 24th. In the following shot it's fixed.
Factual error: When Mrs. Cratchit passes the shop after buying the goose, the sign says butcher, but in that era, you would buy a goose from a poulter, seafood from a fishmonger, and beef, etc. from a butcher.
Factual error: When the messenger has given the photos and materials to the doctor, the data is given to 'DA' or differential analyzer (just like in earth vs the flying saucers). What is shown is a standard card sorter which does nothing but put cards in order. This machine then outputs its info to a standard plotter which can only produce x-y diagrams. It would be easier to do the verification calculations by hand using a slide rule and some graph paper.