It was in Super Mario Kart by the way, not in Super Circuit. (in fact, it was in a romhack, but it didn't alter the engine, only the tracks and textures)
Yes, it happens a lot in this game, considering the shell curves like crazy as soon as you throw it! Sometimes, I'm close to the guy in front of me, I throw the shell at him, he jumps and since I'm too close, the shell spins back far enough and I take the hit... grrr!
Another crazy thing that happened in Super Mario Kart was in 2-player VS race, we were in Ghost Valley, I was Toad with a Feather, and behind was Luigi with a Mushroom. So Luigi uses the Mushroom to catch up to Toad, as he hits Toad from behind, Toad uses the Feather... guess how far did Toad fly off to?