A hidden copyright string crediting Jaleco and NMK (Which otherwise goes uncredited) can be found at 0x078A5 in the main CPU:
(KK) NMK ALL RIGHT RESERVED 1985 PRESENTED BY JALECO
A composer / sound program credit is in the audio CPU starting at 0x0086:
Software and All Songs,Effect Design and Produce By Cheabow. 1986 N M K Limited 1
Only a few of them have specific palettes; The first one here only makes sense with the golden palette, the second needs to use a non-teal palette for palette cycling, and the third needs the teal palette to make its base look right.
An early version of the triangle-shaped ship is in the game. It's slightly different, mostly in the shading of the "eye". The early ship actually uses a different transparent color than everything else, so it wouldn't show up properly in the game anyway.
There are two copies of an early Power-up tile design in the object graphics ROM. Here it is. How about that?