One Piece: Baron Omatsuri and the Secret Island (movie 6)

This film is supposed to be a thinly-veiled allegory about Hosoda's work for Ghibli involving Howl's Moving Castle.

When the Straw Hats entered the city, a globe of the Earth can be seen on the right, which is unusual because it is supposed to be the One Piece world, not the real world.

The girl with sharp hearing, Daisy, has the same name as a very minor character in the Amazon Lily arc who appeared three years after the movie was released.

This movie is quite different from the regular TV series in terms of animation style, character drawings and mood of the story. Instead of the usual light-hearted, sunshine feel, this movie is quite dark and probably not suitable for younger children. Some fans even commented that the ending is "creepy". The movie also contains one of the only times that Luffy has levied a fatal blow on an enemy.

When the crew first arrive at the island, Luffy is seen running in the ocean which should have drained him of energy, like he would usually because of his consumption of the Gomu-Gomu no Mi. This is either a mistake by the writers or it was simply overlooked. But it isn't the first or only time Luffy has frolicked in or around the sea without being largely effected, or at least not instantly, as he maintained the propeller in the Davy Back fight for some time before being sapped of strength. Then again, Luffy's entire participation in the barrel race portion of the Davy Back Fight was a non-canonical addition as well, so it may not be in direct keeping with the rules of Devil Fruit weaknesses.