One thing that bugs me is the transitions between Greenflower Act 1 and Greenflower Act 2, as well as Egg Rock Act 1 and Egg Rock Act 2.
For Greenflower, you're essentially going from the end of a grassy field to the start of a grassy canyon.
For Egg Rock, you go from a hallway to an upside-down elevator.
The transitions between Act 1 and Act 2 of other zones make a bit more sense:
- Techno Hill Zone: Ends off in a factory, starts in said factory.
- Deep Sea Zone: Ends off in a small tunnel, starts in basically what could be the end of said tunnel.
- Castle Eggman Zone: Ends off by entering the castle, starts in the castle.
What I would recommend doing to make the transitions seem a bit more smooth:
- Greenflower Zone: Make the walls at the end taller.
- Techno Hill Zone: While I am already satisfied with the transiton between Act 1 and Act 2, it could be improved a bit. Perhaps add buildings in the background near the end?
- Egg Rock Zone: Have Act 1 end in or just outside an elevator.