Can't remember the exact year but I'm thinking '91 or '92. Went on a short trip to Pigeon Forge, TN and stopped by this outlet mall. I was browsing around in the toy store and noticed they had an endcap of SMS consoles and systems, right out in the open, which was rather odd. I didn't pay a whole lot of attention to it since I had most of the games but what floored me was there was a game I'd never even heard of called Double Hawk.
I walk up to check the Genesis stuff out behind the counter and my mind is blown: half the titles actually say "Mega Drive" on them. Hardly any of them are shrinkwrapped and most just have a small Sega sticker on the side holding the clamshell together. I sheepishly asked the clerk if she could open one for me because in my mind Mega Drive meant Japanese games which I obviously couldn't play. I explained that to her and she looked at me a bit funny, but grabbed Toejam & Earl and popped it open, only for me to see a US style cart! My brain locked up and I had no idea what was going on. I knew something had to be up because right there was Sonic 1 with a Mega Drive label on a white background, nothing like the US version, but the shells weren't Japanese?
I ended up buying Wings of Wor (US version) for either $15 or $20. I had no idea until years later that what I was looking at was a gigantic stock of European games that somehow wound up in an American store. I kick myself in the ass for passing on the import version of Captain Silver, Double Hawk, and other SMS games going for $10 or less. Now that I know what was going on, I always wonder what happened to the people that bought all those PAL consoles only to have them not work.