Goofs

After everybody has gathered to fight Bahumut Sin, they are all on or near the ground. This is followed by a short scene lasting no more than a minute. Cloud then proceeds to jump up the tower, aided along the way by his companions, all of whom were stood around him on the ground only seconds previously.

On multiple occasions during Bahamut's attack when the people are running in fear, some people can be seen passing through each other.

In the scene when Cloud comes to fight Bahamut, while taking the sword from the bike, the sword model is briefly seen passing through the other sword model.

In the original version, when Sephiroth beats down Cloud, Cloud is resting against a wall. Just before Sephiroth stabs him, notice Cloud's ear and turtle neck. His turtle neck goes through his ear.

In the scene where Cloud is on the side of the building, standing on his sword, you can see the smaller separated blade pass through the model of the larger outer sword's handle.

During Sephiroth's opening monologue before he and Cloud begin to fight, when he says "What I want, Cloud...", you can see through his hair to his earlobe, where his hair should be thicker and you shouldn't be able to see the part of his ear that it covers.

When Kadaj summons Bahamut he uses a Green Materia when he should have used a Red Materia (in the game red materia calls forth summons, green materia is for magic).

During the bike chase sequence, Kadaj bursts through a barrier reading: "WARNING: Authorized Parsonal Only." "Personnel" is the correct spelling. This error only appears in the original version, and is corrected in Advent Children Complete.