Austin Powers: International Man of Mystery - Hat and Girl/Man
In the first part where the man/lady gets punched, you can see his/her helmet FLY off. Then when the screen come back IT'S wearing it. And you can see a different person!
Three words for you:
The first is "JOKE." Hello? Where were you when Austin said, "That's not a woman, that's a MAN, man!" Everyone thinks Austin is such a good spy that he could see through the disguise, but then we see that it wasn't really such a great disguise at all.
The second is "PARODY." The whole movie is a parody of really bad 1960s spy movies. In those movies, there were a lot of bad editing cuts resulting in slip-ups like this. This is not a slip-up, because it's making fun the other movies for all their slip-ups that should have been caught.
Finally, the third word is "REPOST." This same slip-up, or should I say, non-slip-up, is already posted under "Magically Reappearing Hat."