Battle Stages in the Mario Kart DS beta.

Differences:
Block City (mini_block_course):
Textures.
SEQ_CIRCUIT2 music.
Lacks both an overview map and a mini map.
boss_donketu object was removed from the final version.

Block Fort:
Not a difference, but trying to play Block Fort with grand prix race settings causes a crash. Loading it in battle mode works fine. I didn't realize this at the time, so I had to use an alternative method.
Different background. Odd goofy faces on the clouds.
SEQ_CIRCUIT2 music.
Lacks a mini map. (?)

Pipe Plaza:
SEQ_CIRCUIT2 music.
Different background.
The collision is pretty messed up.
Pipes don't work.
Due to the lack of invisible walls, you can easily get stuck in a corner.
Lacks both an overview map and a mini map.
mini_dokan object is missing.

Nintendo DS:
SEQ_CIRCUIT2 music.
Different background.
Different images on the screens of the Nintendo DS.
The course has different collision. You can drive on the edge of the stage and the bottom screen has little 'hills' around it.
Lacks a mini map.

mini_stage2, mini_stage3, and mini_stage4 are clones of mini_block_course.

0:00 mini_block_course
0:35 Block Fort (mini_block_64)
2:06 Pipe Plaza (mini_dokan_gc)
3:50 Nintendo DS (mini_stage1)
5:05 mini_block_course Clones