Secret Ending
To get a secret ending movie, beat the game with 99 Dalmatians, all Keyholes locked including the Hundred Aker Wood, and the Hades Cup completed.

Find Torn Pages/ Unlock Mini-Games
After completing the second Traverse Town quest, an old book appears in Merlin's House. Specifically, it's a copy of Winnie-the-Pooh, although it's missing a few pages. To restore the different locations to Pooh's world, and in the process unlock a wide selection of mini-games and hidden items, find the following Torn Pages:
Traverse Town: Rescue 51 Dalmatians.
Agrabah: Dark Chamber in the Cave of Wonders.
Monstro: Chamber 6.
Halloweentown: The bookcase in the Doctor's Lab.
Atlantica: Ariel's Grotto.
Note that you can find the pages in any order -- the sections of the Wood are unlocked in the same order regardless of which pages you bring back when.

New Weapons
Sora, Donald, and Goofy acquire new weapons as they go through the game -- Keychains for Sora, Shields for Goofy, and Rods for Donald. Some are acquired as a matter of course, while others are rare and require a little wandering out of the way. Also, periodically go back to the Item Shop in Traverse Town to see the nephews' new stock. Here's where to find what:

Sora -- Keychains
Kingdom Key: Default.
Jungle King: Clear Deep Jungle.
Three Wishes: Clear Agrabah.
Crabclaw: Clear Atlantica.
Pumpkinhead: Clear Halloweentown.
Fairy Harp: Clear Neverland.
Wishing Star: Go back to Traverse Town after clearing Monstro and see Geppetto at his shop in District 1.
Spellbinder: See Merlin after acquiring Fire, Thunder, and Blizzard.
Metal Chocobo: Beat Cloud in the Hercules Cup.
Olympia: Beat Phil, Pegasus, and Hercules Cups.
Divine Rose: Seal Hollow Bastion and see Belle in the Library.
Oathkeeper: Talk to Kairi in the Secret Waterway after the first trip to Hollow Bastion.
Oblivion: In the Grand Hall in Hollow Bastion, during the second trip.
Lionheart: Beat Leon and Cloud in the Hades Cups.
Ultima Weapon: Synthesize at the Item Shop.
Goofy -- Shields


Knight's Shield: Default.
Stout Shield: For sale at the Item Shop in Traverse Town.
Smasher: For sale at the Item Shop in Traverse Town.
Mythril Shield: For sale at the Item Shop in Traverse Town.
Gigas Fist: For sale at the Item Shop in Traverse Town.
Golem Shield: For sale at the Item Shop in Traverse Town.
Onyx Shield: For sale at the Item Shop in Traverse Town.
Adamant Shield: For sale at the Item Shop in Traverse Town.
Herc's Shield: Beat the Hercules Cup.
Genji Shield: Beat Yuffie in the Hades Cup.
Defender: A rare item dropped by Defenders in Hollow Bastion.
Save the King: Beat the Hades Cup time attack.
Donald -- Rods

Mage's Staff: Default
Morning Star: For sale at the Item Shop in Traverse Town.
Warhammer: For sale at the Item Shop in Traverse Town.
Shooting Star: For sale at the Item Shop in Traverse Town.
Magus Staff: For sale at the Item Shop in Traverse Town.
Silver Mallet: For sale at the Item Shop in Traverse Town.
Grand Mallet: For sale at the Item Shop in Traverse Town.
Wisdom Staff: For sale at the Item Shop in Traverse Town.
Lord Fortune: Get every summon and visit the Fairy Godmother.
Violetta: White Trinity in Olympus Coliseum.
Wizard's Relic: A rare item dropped by Wizards in Hollow Bastion.
Dream Rod: Acquire every spell and visit Merlin.
Save the Queen: Beat the Hades Cup solo.

Hints:

In order to beat the phantom in Neverland you must use your magic. First, go to the cabin tinker bell will be there but you must switch to Peter Pan in order to talk to her so you'll have to trade either Donald or Goofy. Then after talking to her it'll cut to a cinema and you'll see the phantom. When you lock on to him it'll be his heart but it will appear and dissapear at times. When his heart is blue use blizzard, red fire, yellow lightning, and when it's a pale white color just take as many hit you can get out of him. By the way, if at any time you see numbers above your head or the head of your party use the stop spell on the clock. Try to be at a high level when you battle him at least Lev 65 and have many hi potions with you in case.