It is an urban level with many springs and bumpers, resembling a pinball machine. There are many secret areas in this zone. Act 2 has two Robotnik signs (goals) and as such, can be ended through two possible routes. This second route is accessed by jumping off of the ramp with the trail of rings on it.
Spring Yard Zone was supposed to called Sparkling Zone. It also was originally not an urban city with mountains, but rather a luminous place with buildings at night time with neon signs and shiny stars just like a typical casino level that would feature in later Sonic games.
This was originally intended to be the fifth zone of the game.
Spring Yard Zone was the first zone created and finished.
This is the earliest zone by which all six Chaos Emeralds can be obtained in Act 2 of this zone.
The theme of Spring Yard Zone sounds similar to the 1987 composition " Lovin' You 'Sawako' " by famous Japanese jazz guitarist Toshiki Kadomatsu (background structure stripped of the solo/foreground instruments/harmony vocals part after solo in the early second minute mark is extremely easy to spot).