Here's a daft and unimportant one -
If you have the Console Emulator on a track, it has no needles showing before you turn it on. They appear when you turn it on, and stay there when you turn it off again.
This doesn't happen with busses.
I guess that some routine that paints the needle isn't being called until the CE is turned on.
It doesn't matter in the slightest, but just thought I'd point it out.