Revealing mistake: At the first challenge, just before the Horntail makes its appearance, there is a tight close-up of the egg as Harry stands in the stone "doorway" in the background, on the left. Clearly it is not Daniel Radcliffe, but his stand-in (his face differs and he has a shorter, bowl-type haircut) who is standing there, for this one specific shot.
Suggested correction: I watched this scene more than once and I never noticed any stand-in. I would need a picture to prove it. Besides, why would they need a stand-in in this scene?
Continuity mistake: When the Polyjuice Potion wears off, Barty Crouch Jr. resumes his own appearance from impersonating Mad-Eye Moody. It is difficult and painful. Every other time we see this transformation in other characters, it is easy and uneventful.
Suggested correction: It is probably a strain for him since he has been in the shape of Moody for a year. Or he is trying to prevent it somehow, or it is withdrawal symptoms. It's a magic potion; it could be anything.
