Mr & Mrs Beaver's costumes were notoriously impractical in the snow. So much so that in outdoor scenes, a couple of assistants, nicknamed the "Beaver Retrievers" had to stand around to pick the actors up, if they slipped over.
Plot similarities between the J.R.R. Tolkien Lord of the Rings trilogy and C.S. Lewis Narnia stories was no coincidence. Both men were members of a literary discussion group known as the Inklings. Living trees that move and fight but also provide a safe zone, languages created for the legendary cultures within the mythology, rescues from towers by flying creatures are a few examples.
Cair Paravel means "the lower court", from the Welsh "caer" meaning a fort and the old French "paravail" meaning either "lower" or "in the valley".
Aslan's mane was made from real yak hair. The eyes were made softer than a real lion's, while the face had animatronic functions. Two people were inside the lion, somewhat like a pantomime horse.
Before his death, C.S. Lewis sold the adaptation rights to the entire "Narnia" series. At that time, he absolutely despised television adaptations of his books, believing they were non-realistic, since actors had to wear suits to play non-human characters.