Interesting topic. I don't think they had any blockbuster version. Genesis already came in a clamshell, so it would make sense that is what they used. They would slap a sticker with a bar code on it and rent it out.
I did find this one, but I'm not sure if it got in the yellow case until AFTER blockbuster sold it (direct link below)
Sega Genesis Green Dog The Beached Surfer Dude Game Blockbuster Rental 1992 | eBay
Hope this helps!