All stages:
- Please use an underscore "_" in the .def file names.  IIRC, having a space in there can cause problems for people who order their characters.  Using apostrophes might also have some ill effects.

Underground HQ:
- Levels in the far back repeat way too noticeably.
- Walls above the Rolento posters are a bit to plain, maybe add some cracks or texture.
- You could probably use the light flickering animation on some of the other floors and randomize them to help differenciate.  You could also possibly have the lights on the ceiling flicker.
- Edge on the top back of the train looks a little funky...is that from the source?

Spanish Ninjitsu:
- Edges of the top of the tower could use a little work with the aliasing.

Thailand:
- Lots of dead space between the statue and beginning of the clouds.  Maybe bring them down a bit and edit them so they can go up higher, possibly add some birds flying by, I dunno.
- Very nice work on that foot, but could use a little work on the edge of the arches.

Trainwreck:
- Hanging wire is noticeably not attached to anything, not sure what else you could do with it though.  Perhaps edit it to continue upwards, and attach it to another steel beam?

Charlie's Fight:
- "Jazz" sign could use some more work.  The angle of the edited letters looks off.
- You should put the far background on a smaller Y Delta to give the stage more depth.  You could even separate the buildings from the sky to give it even more.

Sakura's House:
- Telephone poles could use a lot of work.  There should be three wires for each pole, two on one of the supports, and one on the other.  Check this pic for reference: - The pole on the right is missing the support on the right and the third wire.
- The pole on the left looks very distorted at the top, and two of the wires are running to the wrong support.  The top of the pole is also very boxed off, could be rounded to look better.
- The clouds on the right, behind the pole, have a straight edge, which makes them look unnatural.
- The pipe on the left side of the house could use some work on the aliasing.
- Aliasing on the top floor shutter could use some work.