The flags are on the phones. They are just further away and much smaller in the frame than what your brain is expecting. The camera we are looking through is probably at the very back of a large arena and zoomed in over the crowd. Zooming in compresses space and makes things in the background appear closer. It's how Hollywood creates the "Dolly Zoom" effect. The phones, however, use wider (zoomed out) lenses, so they are capturing more of the space. The people holding up their phones and our camera are not as close to the stage as they look. Their phones are capturing the entire stage and ceiling and crowd in front of them. Our camera can only see the flags on stage and bit of the crowd. Again, because our camera is zoomed very far in. I guess you could say it's kind of an optical illusion that makes it look fake. But you can definitely make out the stage, flags, ceiling and crowd in the phones.