When Susan is writing Lucy and Edmund a letter, the camera pans to a high quality, color photograph of the four siblings in uniforms. Color photography was only rarely used by professionals even 5 years after WWII ended and would never have matched the modern clarity of the prop photo.
When Lucy places the sixth sword on Aslan's table, there are twigs scattered around and under the swords, but the next shot shows all six swords lying in a clear spot on the table with hardly any twigs.
In The Chronicles of Narnia: Prince Caspian, Caspian (Ben Barnes) spoke with a pronounced Spanish accent, as did the other Telmarines. In this film, Caspian now speaks with an English accent. This is done purposefully by the filmmakers, who no longer needed to match Caspian's accent to the other Telmarines, so they chose to use the actor's more realistic natural British accent. People's accents change over time in real life as well.