Teen Titans: Trouble In Tokyo (2006)

Factual error: Throughout the film, most Japanese words are spelled in Katakana. In real-life Japanese, however, Katakana is exclusively used for foreign words adopted into Japanese language, like 'table', 'television' (mostly it is abbreviated to 'telebi') and 'racing car'. But in the film, even indiginous Japanese words such as 'samurai' are spelled in Katakana, not - as they should be - in Hiragana (the syllable system used for native words).

Robin: I'm a hero, Starfire, and if you don't like it.
Starfire: Robin? I like it more then you will ever know.

Trivia: For those who are interested in what Nya-Nya (the Catgirl) says to Beast Boy during their first fight: She first tries to tease him by saying how much she likes to get him angry. Later, after she kisses him on the cheek, she says, "Close your eyes. It's gonna hurt."