Two sets of unused graphics can be found in the ROM using an image viewing program such as Tile Layer Pro.
Oddly enough, during normal gameplay, the infamous Charlie Brown is nowhere to be found. However, sprites for him are still in the ROM!
The Charlie Brown sprites are found just below the sprites that are used for the Pogo event, so it is a very likely possibility that he was meant to be used there, perhaps waiting for Snoopy and Spike at the finish line, since there is a sprite of Charlie Brown facing left, but not right. The other two sprites look to be used once Snoopy or Spike crosses the finish line. It's also quite likely that he would have shared Woodstock's palette, since Woodstock uses two colors and the third color could have simply been a flesh-like color.
Unused Title Graphic?Edit
There is an image of Snoopy on a bike that is unused in the final game. Because of it's position in the tileset of the ROM, it could have been used as a title image before they replaced it with the big Snoopy in the bowtie.
Source: Rick L.