At least in the mexican eShop, in the coming soon shelf of the eshop, they list "Finding Nemo Escape to the Big Blue".
The info bit mentions it's the 3DS version of the game, but the screenshots and the banner are for the DS version.

So, is a DS retail game coming to the eShop or is the eShop showing the wrong images?

It's not the only odd thing they did today either. They put the Hello Kitty game for sale for 20 pesos too (that's less than two dollars).

I would assume that its a 3DS game on the eShop since there has not been any mention of DS games coming to the eShop. Of course you can always contact Nintendo and ask them to make sure.

they probably put the ds images by accident because there is a 3ds version of the game

I guess it is the 3DS version... It's still weird to see images from the DS game :S

Technically, it is the first DS retail game with images on the eShop.

iirc Disney or whoever owns the rights to publish the Finding Nemo game upgraded a GBA or DS version of the game a few months ago and re-released it to coincide with the movie's 3D re-release. Considering we've never had a true DS retail release on the eShop (DSiWare releases of DS games aside), I'd say it's the 3DS version. How much/little work was put into the port, however, I can't tell you; it may just be the laziest port ever.

why does nemo always get lost...