This logo appears before the title screen. It looks like it was originally to be an animated SEGA logo in FMV, but was later discarded. It also uses the classic 'SEGA' voice. This was probably taken out because the Mega CD BIOS has the SEGA logo anyway before startup.

The title screen for Sonic CD between 510 and final changed dramatically. Firstly, the game was named 'CD Sonic' originally, possibly a take on the SEGASonic name used in Merchendise. The background is lighter with the Little Planet clearer to view in the sky, and bobbing up and down at a faster rate.

Eggman mountain was made taller with more classic styled grass surrounding it, and a SEGA Logo was added to the bottom of Sonic's banner. Text is at the bottom twlling you who did the Vocals for Toot Toot Sonic Warrior, probably for previewers who wanted to mention it.

For comparisons sake, this is the final title screen taken from Sonic CD PAL. Notice how the clouds were also changed to be in Mode 7 style rather than scrolling across like Sonic 1. The resolution was also changed for the title screen because of the Mode 7, using 256x224 rather than 320x224. This resolution was also used for the Special Stages.

Lastly, the 'new game' text was changed to be where the SEGA logo once was, and instead of switching by pressing up and down, you choose your option by pressing left and right.

In the Time attack selection, the Exit image was changed at a later date. The 510 version has a picture of the Little Planet, while the final has a smaller rendition of the title screen.

Once you finish the first three levels in 510, the game leaves you with this scrolling message. Click it for the full version.

There is also a very early levels select avaliable by pressing Start in Player 2's controller on the title screen, and pressing start on Player 1. The final is very similar, just with a better looking interface.