This it just for showing the mind boss of 4-2.
At the end of the level you get to this unfinished cutscene of the elite trios from the Mario a Luigi series.
After this cutscene you will in a room with other enemies like in SMB3 but instead of Hammer bro you will be with other enemies.
The Door you see is just for testing
image of the exit to the Ice Cave.
Userbar made by Green Jerry