This area is where those green smasher objects should come down. Also, the "torch fire" is missing in the background.
Ufos in the background
If you use the debug on sonic 1, you can place the pink spiked badnik in the Marble Zone. Otherwise, it's not in there. But in this version, it seems they were in there. Also, the UFOs didn't make the final game as well. I also remember when I had a poster of Genesis games, this was in it.
Another shot of the UFOs
really weird mz with tiles falling....
sideways spikes. Also, the "torch fire" is missing in the background.
Unknown area in Marble Zone