Labyrinth Zone was going to be the second zone, according to the unaltered Level Select menu, but due to its high difficulty compared with the earlier stages, it was put as the fourth zone in the final version. Due to at that point was in development, there are some sections empty with no water, and Act 3 had a completely black background. In Labyrinth Zone, the background was dark rocky with ceiling crystals (similar to this Zone in the 8-bit version), the crystals were a bit smaller. Sonic & All-Stars Racing Transformed Review This version was in the Consumer Electronics Show March 1991. The differences are less evident, though the Debug Mode is present. There was a rolling ball in which the player could move by pushing it, which was later used for the Egg Wrecker boss fight.

The layout was different the Ball Hogs were present in the level, along with the Robotnik monitor that later debuted in Sonic the Hedgehog 2. In the second beta iteration of Green Hill, elements such as the taller purple flowers and the strikingly close water/sky shades of blue in this build did make their way in the finished version. The second early iteration of Green Hill Zone. The rocks were originally orange they were not a layout obstacle but instead found in the foreground along with the palm trees being independent from the clouds and other objects in the background, all separate from the scrolling of Sonic as he ran through the hill-like terrain, similar to those light posts from Star Light Zone. There was a signboard giving the welcome to Sonic, in which it is thought to say: ' You Are Welcome Sega, Sonic', with a picture of a palm tree in the top right hand corner. Green Hill Zone was initially different the sky was darker than in the actual Zone, the conical mountains were normal mountains (they appear to be close in the background unlike the final version of Green Hill Zone) with few small waterfalls and no river to be found, and the clouds are bigger. Of note is that in the interview, Naka claims that this tech demo was planned at one stage to be included in Sonic Mega Collection, but was never in any build as the ROM has since been lost internally at Sega. In a retrospective interview with Yuji Naka, it was revealed that the original Sonic Team put together a small, playable technical demo for the show featuring Sonic in an early version of the Green Hill Zone. The first glimpse of Sonic the Hedgehog in video game form was at the Tokyo Toy Show in June 1990, which also happened to be the first time the game could be played by the general public.

Sonic 1 swimming sprites