They were out of frame. Out of the 4:3 frame.
Edit: I jumped the gun and thought we were talking about the Friends screenshot.
But it was never intended for 4:3. They were always in frame, just digitally removed.
No the original was 16:9, you can see they have been digitally removed in the shots from the Blu-ray.
But it was never intended for 4:3. They were always in frame, just digitally removed.