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.
Caspian hands Edmund the torch he had left behind three (Narnian) years earlier and it still works (as shown by Edmund's using it to confuse the sea-serpent in the Island of Darkness fight). Even using the book's one year passing in England, the zinc-carbon batteries in the torch would have been discharged long prior, and also leaked (spoiling the entire torch). Alkaline dry batteries (which could possibly last that long, as inferred from a commercial for the Duracell brand) were not commercially available until the 1950s (the patent for these was filed 1957/10/09, and granted in 1960).
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.