Just about every time I go through a tunnel there is a static pop with the music.
Enemies can also pass through asteroids without dying.
With the upgrades if you pass a sphere but there is a upgrade flying around they themselves can travel through the tunnels. When this happened to me it floated around in a different sphere for a bit and it came back through to the sphere where I was at, then went into a tunnel that went further away and despawnd. Don't know if the despawn was from a timer or from distance.
I do suggest with the upgrade bug to maybe not have the tunnels open unless there are no enemies, asteroids or upgrades floating around.
P.S. Great game so far! :D