WMG / Bedknobs and Broomsticks

The movie takes place in the Harry Potter universe and Miss Price is an undetected Muggleborn

Rather obvious, really. One can only assume something went wrong with that muggle-born-recording book; the Ministry never noticed, possibly because, being calm and collected, the young Miss Price showed very little accidental magic that could have set off the Magic Trace. Miss Price only started doing magic when she began to follow Emelius Browne's correspondence course, and by that point, the Ministry had more important things to do than investigate an unregistered magic user, especially considering Miss Price's careful discretion meant she was no immediate threat to the Statute either way: this was right in the middle of Grindelwald's War, the most devastating magical conflict the Wizard World had known until Voldemort came along. (The Spells of Astaroth was written before the Statute of Secrecy was inforced, and, by the time it was created, was believed lost until it turned up in the hands of the Librarian.) Emelius Browne is what is known as a 'Late-Bloomer' (J.K. Rowling mentioned them in Word of God even though they never actually appeared in the books): people whose magical ability only awakens in a very stressful situation at any point of their life, rather than slowly building up through childhood. This explains why he was able to do the 'Turn Into A Rabbit' spell in the climax.

Substitutiary Locomotion is the same spell as Piertotum Locomotor, or at least a variation thereof

They both do the same thing - bring empty suits of armor to life to be used in battle. Which leads us to...

Miss Price is actually Professor McGonagall

Or conversely...

Miss Price is Professor McGonagall's mother.

They did accompany each other on a pleasure cruise.

Substitutiary Locomotion doesn't just animate inanimate objects with energy.

All the items we see under the power of the spell seem to have odd personalities and quirks to them, and for the ones whose owners we know, these seem to relate either to their owners' personalities and quirks or subconscious feelings and desires of those owners. Professor Browne, who is a cheeky fellow but also likes Miss Price a great deal, has a pair of shoes that boot her in the rear; meanwhile she has feelings for him she is denying/suppressing, and her nightgown approaches him to dance (and chases away the vicar whom she is not interested in). Carrie and Paul, who just want to have fun, are seen dancing and playing with their own clothes—except when Paul is being 'disciplined' by Miss Price's pantyhose (she had just warned him to calm down and stop making a ruckus). Charlie, meanwhile, gets to be on the receiving end of his own troublesome, rebellious nature courtesy of his Sunday pants. Even the vicar, who harbors a not-so-secret desire to voyeuristically pry into Miss Price's life so he can romance her, has his hat go flying inside to investigate.

This implies, then, that the suits of Animated Armor are not merely animated by magic, but by the spirits of the dead soldiers who once owned and wore them; this, as much as the age of the armor, would explain why they responded to the ancient, old-fashioned way of speaking the spell words instead of needing the 'modernized' song-and-dance number, because it was familiar to them. This also explains why the armor gradually sinks to the ground when the spell is broken instead of simply dropping, to visually signify the spirits returning to the Other Side as their armor "died" again.

• It also explains the way everyone's clearly looking at each other with a 'are they with you- nope' glance when the bagpipers start playing. After all, most of them were English soldiers, so what's a Scot doing there?
  • Also, the Viking-style armor looking around in puzzlement, as if a bit startled to be fighting alongside the rest instead of against them.

Emelius Browne is just a stage name.

Professor Browne's real identity is Michael Banks. Michael was exposed to magic early in his life, and it's quite likely that he developed it into an act later in life. Add in a case of Identical Grandson, and it makes perfect sense.

• If he looked like Ben Whishaw in the 1930s, it's unlikely he would look like David Tomlinson in 1940.
  • That, however, could simply be a case of The Other Darrin. Sean Connery looks nothing like Roger Moore, but most audiences (repeat: most) are willing to accept that they play the exact same character.

Our heroes never actually went to the real Island of Naboombu.

Common sense dictates that Real!Naboombu, colonized by anthropomorphic animals sometime in the Middle Ages or Renaissance, would be a rather sinister Dr.-Moreau-ish place (assuming the animal colony still exists some 500 years later, which itself is open to reasonable doubt). What's more, one would expect that a location in the real world would be filmed in live action, to match the rest of the movie.

But where does the bedknob take our heroes? To a colorful, not-particularly-sinister, 2D, animated world that looks exactly like the one in Paul's storybook. Inevitable conclusion: when it received orders to go to Naboombu, the ever-literal, ever-pragmatic bedknob took them to the closest location with that name ... the one inside the book itself.

This explains why the Star doesn't travel back with them (it's just a drawing in a book and therefore can't transfer to the real world), why there are so many African animals on an island supposedly colonized by the menagerie of a European astrologer (the animals are just the figments of a book illustrator's imagination), and why those animals, despite being cut off from the real world for 500+ years, know the game of soccer (more artistic license from the illustrator).

So how did this early-20th-century book illustrator know about Naboombu at all? Easy: the illustrator had access to a complete copy of The Spells of Astaroth, and thought it was absolute bunk, but decided it would make a good children's book. That, in turn, explains why the drawing of the Star has the actual spell on it: the illustrator, much like Emelius, was just copying fun words out of an old book, and was totally unaware of their true powers.

• Alternately, there is no "real" Island of Naboombu, because the Star created it as a pocket dimension inside the book to ensure humans couldn't easily sail there one day and interfere with the animals' development. The book was never written, but was spontaneously generated (complete with bogus backstory about a sailor landing there) by the Star's magic.

• Either way, this would explain why Miss Price describes stealing the animated Star as transferring it "from one world into another."

Emelius's house is the most magical thing in the whole movie.

All we really know about Emelius's house is (1) that it was abandoned by its true occupants during a bomb scare, (2) that the bomb never went off, allowing Emelius to take up residence, and (3) that the house's library inexplicably contains both the Naboombu storybook and an incomplete but useful copy of The Spells of Astaroth.

Contrived Coincidence much? Absolutely—unless the house itself is influencing the course of events to prevent Astaroth's magic from being destroyed. First it causes the children's book pertaining to Astaroth to come into its domain; then it protects it during the Blitz by making that Nazi bomb never go off; then it manipulates history in such a way that Emelius just "happens" to be in the area, just "happens" to move in, and just "happens" to bring at least half of the tome there. All because the house is in a life-or-death struggle to make sure Astaroth's spells eventually end up with the best possible caretaker for them: Miss Price.

And the house cares about all this, and is magic and sentient in the first place, for a very simple reason: it was built on the site where Astaroth worked. Elementary, my dear wizard.

Astaroth didn't die.

He's a medieval or Renaissance alchemist along the lines of Faust, his spells actually work, and his name is the same as one of the Crowned Princes of Hell. In other words, the implication is extremely strong that he sold his soul to the Devil in exchange for magical knowledge and immortality.

When his anthropomorphic animal experiment backfired, the animals tried to kill him. Since the Devil's charm was already on him, however, he didn't get a Disney Villain Death; he got a Disney Death. He was only beaten unconscious. When he came to, all his magical apparatuses had been stolen by the animals, and the concussion had given him amnesia. All his magical knowledge was gone, and now he was forced to live an eternity trying to get it back. (Well, what do you expect from bartering with the Devil? A happy ending?)

During the next 500ish years, he slowly worked out what had happened and who he was, and eventually he got hold of a pirated copy of his spell book—but the first half of the book was missing, so all he had was indexes and appendices and biographical information about himself. From that moment on, he's devoted all his energies toward finding the missing first half of the book, the half with all the spells in it. He's especially anxious to regain his greatest discovery, the Substitutiary Locomotion incantation. There isn't much he wouldn't do to get the spellbook complete again.

Which is why, in the 1940s, he's working as a sinister and very mysterious Bookseller in Portobello Road.

• This is an excellent WMG, explaining a LOT about this Bookseller character. Also, why did all that "Brown wanting to buy the book and the bookseller saying that the coin was fake" thing happen ? Astaroth had hidden his (recently recovered, complete for a few hours only) book where no one could find it: among a BUNCH of other books, with the thought of course that no one would be interested in it. When Brown wanted to buy it, he refused, arguing (a lie) that the coin was fake, and wanted to keep the book, by force if necessary. He failed and the book was broken in two halves, before the sorcerer could have reread the book.

After the War, Carrie went to Cackle's Academy For Witches.

She has first hand experience with magic, and is of age. she could have gotten in with a scholarship.