Here is where we post all those rumors about the game that we know or have heard of, both fake and true.
I'll start with this.

If you get to the city of the ancients before the gamer clock hits 4 hours, Tifa will be killed instead of Aeris. - obviously false.

If you use gameshark codes to get Yuffie into your party before the midgar zolom crossing, she will have her own unique sentence that she says when you look upon the midgar zolom impaled on the spike - Oddly enough, this is true. The significance of this is that its impossible otherwise to get yuffie before the crossing.