A Mattel spokeswoman told the BBC: "It's just an unfortunate incident where someone from the production company thought they were just putting in random text.
"We have no reason to believe it was done maliciously."
In a statement, Mattel said: "The page was intended to show illegible text and we deeply regret this error.
"We sincerely apologise for any distress or offence it may have caused."
It said it would "no longer be working with the animation studio responsible", and would take "immediate action to remove this episode from circulation".
"We are reviewing our content production procedures to ensure this never happens again," it added.
By Patrick Evans, BBC's Social News and UGC Hub