The Lion King - NES

[MarioMania]

Can someone explain to me why does the game flips out on a NTSC NES??

[nintendodork]

Because of the region lockout most likely.  The game was never released in the states.  If you have a toaster that hasn't been modified at all, it's going to do that.

[NintendoKing]

Here you go, I made this guide; it should help you.
Otherwise, buy a NES-101 Toploader, they work with all games... except Famicom unless you have a pin converter.