I've found two major bugs in the Subsea track. Both have been there since 0.7.3.
1. The pillars in the pirate's cave are hovering. You can also see that they have hollow insides. Remember: Blender is polygon mesh modeller.
2. When you die you go through the roof... literally. This is because you sort of come a ghost I think BUT some of the time bouncing balls will do it to. Then they will land on the top of the tube and bounce off. In other words they go out but not back in. When it's bouncing up above it's no use to anyone.