Things I would change :
- the black buttons IMHO are a bit too much. I would replace them with black/red buttons, so that they have the colors of the trackball, which would result in a more consistent look. IMHO the black buttons just look out of place.
- the yellow bat-top also looks out of place. I would replace it with a black one, or while we are at it, change all three to red to go with the trackball, black/red buttons.
- the white player 1/2 buttons. I would replace them with yellow ones, buy some decals (player 1/2) and put those on the yellow buttons.
A quick and dirty comparison between CP with black buttons and CP with black/red buttons :

Now imagine the bat-tops being red and the white buttons being yellow and you would get a more consistent look.