It's good to know at least some of Miss Prices's magical items survived the Nazi attack. Maybe they can use that bedknob to get more?
"The Age of Not Believing" is a very sombre song that hits a great note of nostalgia and regret for everyone who remembers the period of disillusionment around that age, but it ends on a distinct note of hope; "at last you start believing there's something wonderful in you". Charlie's Character Development from bratty, abrasive child to caring and sympathetic big brother figure proves it.
It's implied that they're possessed by the spirits of their owners, who are clearly having the time of their lives in kicking the SS troops out of their home.
Just the fact, that Mr. Browne, a con-man who never truly believed in magic, let alone work it, until Miss Price came along, and even then hated her more liberal uses on him when he got of line, finally is able to cast that spell to turn himself into a rabbit, when the people he cares for are in danger. The look on his face is a perfect mixture of Awesome, Funny and Heartwarming. His ears start wiggling, his nose starts twitching but his smile just gets bigger and goofier, as his face is consumed by both joy and magic.