Other mistake: The first victim of the mask in the series falls back against crates that must be made of dry leaves, since all it takes is for the body to lean against them to utterly shatter them. (00:18:55)
Continuity mistake: Dio is gloating thinking that JoJo probably got himself killed in Ogre Street already. A crowd of disreputable individuals zombie-walks towards him; one of the guys in front has some sort of scythe that he holds in opposite directions when we switch to the reverse angle. (00:15:55)
Character mistake: The episode opens showing "The LLUSTRATED morning " newspaper. Yes, it is missing the letter "i." (00:00:15)
