Anyway to tell a fake genesis cartridge from a real one?

So I'm starting to collect some old SEGA genesis games, but I'm worried one of them I bought might be a fake. I bought the first mortal kombat for about 5 dollars case in box. Only thing was it was missing the manual. The game and box look like they have lots of use on them, but there's a few things that make me nervous. It says it's "assembled in Mexico" and the screws look like hexagons. I put it in my genesis and it looks like it boots and plays fine, but I heard playing fake cartridges can actually damage your console.

I heard that a company called majesco used to produce these cartridges and they had "assembled in Mexico" on the back of the cartridge.

Does anyone have any idea how to spot a fake?

Don't know much about the Genesis Cartridges of what to look for, just have like a spare real one (if you have anyone possibly) to compare when buying others. Hope these few videos help you as well!