Snoopy's Silly Sports Spectacular

Snoopy's Silly Sports Spectacular was based on Alternative World Games for Commodore 64, but the C64 version had more games.

Unused Graphics
Two sets of unused graphics can be found in the ROM.

Charlie Brown
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.

In the Japanese version, Donald Duck, Charlie Brown's spot is instead occupied by the text ゲーム (game).

Unused Title Graphic
There is an image of Snoopy on a bike that is unused in the final game. Because of its 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.

Junk Data
Interestingly, in the Japanese version, the 4th PRG ROM bank is padded with graphics from an early version of Ginga Eiyuu Densetsu! These graphics reveal both a spelling error and a subtitle that were removed from the final version of the game.

Regional Differences
The game was originally released as Donald Duck in Japan. Obviously any graphics that are related to Donald Duck were changed to graphics related to Snoopy.