Chopper's Kingdom on the Island of Strange Animals is the third One Piece film in the long-running franchise.
As the title suggests, Chopper takes the spotlight in this one as the Straw Hats manage to make their way to Crown Island in search of the legendary Crowning Treasure Horns. However their arrival coincides with the death of island's ruler, Kirin Lion, much to his adoptive son, Mobambi's, dismay. As such the island waits for it's new ruler signaled by geysers around the island (hence the name Crown Island). The Straw Hats wound up caught in one of the geysers and sent flying where Chopper is thrown off the Merry Go. He lands right in front of Mobambi and the animals who believe him to be the next king since he "fell from the sky".
Meanwhile the Straw Hats, after landing safely, begin their search for Chopper. Coming across a suspicious individual, Count Butler, and his cohorts who are also after the the Crowning Treasure Horns and killing the island's inhabitants to find it. What follows is a race to get to Chopper before Butler does and try to prevent the poacher from getting his hands on the horns.
- Awesome Moment of Crowning: At the end of the movie, Mobambi is crowned the new king for his bravery in trying to stop Butler.
- Came from the Sky: The animals believe Chopper to be their king thanks to this. In truth he was just flung off from the Merry when it went flying and happened to land right in front of them.
- Debut Queue: Most obviously, this is Chopper's first movie appearance, so much so that the film is pretty much centered on him.
- Didn't Think This Through: Hotdog brags about his kick being able to break steel and then kicks Zoro after he's been tied up using the steel chain on his flail. Naturally the chain breaks and Zoro chides him for the recklessness of his actions.
- Epic Flail: Hotdog tries to use one to smash Zoro before resorting to kicks.
- Evil Poacher: Butler. He poaches animals so he can eat their horns.
- Humans Are Bastards: Somewhat explored though ultimately subverted. Butler and his cronies are killing the animals on the island, but are defeated by the Straw Hats, who defend the island, and ultimately Mobambi, a human child, is crowned the new king of the animals.
- Musical Assassin: Butler who can use his violin to mind control animals called Horn Eaters to do his bidding (which oddly affects Luffy as well) as well as wields a tambourine shaped ax.
- Non-Human Sidekick: Karasuke to Mobambi.
- Non-Serial Movie: While most of the One Piece films fit this trope, being non-canonical, stand-alone stories, it's usually easy to figure out when they're supposed to take place in the greater narrative. This movie, however, can't possibly fit anywhere in the timeline, thanks to the absence of Vivi — who was with the crew when Chopper first joined — and Robin, who joined the crew immediately after Vivi left, unless she was just sitting undiscovered in the ship's cabin for the entire film.
- Obviously Evil: Butler. The man even has an outfit with the word "evil" on the back, for crying out loud.
- One-Winged Angel: When Butler eats the Treasure Horns, he becomes a hulking beast. Once the horns are destroyed, however...
- Playing Against Type: In-universe and meta example: Normally Zoro and Sanji would battle the swordsman and martial artist respectively in the Big Bad's Quirky Mini Boss Squad. In this movie, it's reversed — Zoro goes up against Hot Dog, a man who attacks with kicks, while Sanji fights Heaby, a swordsman. After defeating their respective opponents, both Straw Hats say their opponent's attacks could never match up with their crewmate's.
- Punny Name: Karasuke is a pun on Karasu (crow) and Suke, a typical suffix for Japanese names. Heaby sounds like Hebi (snake).
- Raised by Wolves: Mobambi was taken in by a Lion-Qilin hybrid animal after he wound up shipwrecked on the island.
- Red Baron: Hotdog "The Crazy Dog" and Heaby "The Poisonous Snake."
- Reused Character Design: A lot of the background animals on Crown Island are obvious recolors of various creatures from Gaimon's island (in fact, the kanji for "Island of Strange Animals" in the film's title is exactly the same as that used for Gaimon's island). All the Straw Hats' outfits are also taken from various color spreads and covers Oda drew in earlier years.
- Short Film: Just a little under an hour in total.
- Talking Animal: Two in the movie; Karasuke, Mobambi's friend and a bald parrot who acts as an old sage for the kingdom.
- Whip Sword: Heaby's weapon of choice. According to Sanji, it's nothing compared to Zoro's.
- You Killed My Father: Mobambi to Butler.