Located at 0x099C is a build date along with developer credits:
SMSG 3.06w Jason Andersen/John Schappert 8/15/1993
An unused song can be heard at the title screen and menu screens by using the ROM address C087DB89. Its bass line is a slower version of the bass motif in the title screen theme, while the horn line resembles the melody of "Blister in the Sun" by Violent Femmes.
This song is used in the prototype with a 1-in-127 chance per level to be played, whereas there's a ghost of a chance that the song will play in the retail versions.
A leftover from ClayFighter.