All the faces in the background are the same.

You may have been looking to closely at the women in the foreground. Nothing is off about them.

But in the background, everyone has the same head. Someone edited the image so that everyone's head was replaced with one belonging to a curly-haired guy looking down.

The image's trick is a good reminder that the details you're looking for aren't always in the foreground. Sometimes they're in unexpected places.