There are odd black squares (Block 84) that are used in certain chunks.

This also let the developers add objects like monitors and springs to the loop tops. The top of the loops have spotty collision in the prototype that doesn't match the actual art the final version fixes this by adding a solid flat surface to the top of the loop.

In the Simon Wai version, the loops are very thin.

Since these are frequently used in floor chunks, this is a bit of a problem.

The pink diamond blocks and would-be animated blocks aren't solid at the top.

Those blocks will either be blank (if accessed from the Level Select before any demo plays) or use whatever tiles were loaded in VRAM from the previous Zone (as seen above, where the tiles come from Hill Top).

There are certain 16×16 blocks that call for animated tiles in range 3E8-3F7 in the Simon Wai version, but no animated tiles are loaded to those slots.

This leads to the player(s) spawning slightly above the ground in Act 1 and way above the ground in Act 2.

The starting positions for Sonic and Tails are taken from Emerald Hill.

Casino Night is the only zone to do this. However, they are identical between acts.

For some very odd reason, there are two different palettes defined and used for each act.

This includes the objects that make the triangular bumpers, conveyor belts, and loops work. There are no objects at all in the Simon Wai layout.

Sonic 2 casino zone