Corrected entry: Rufus Shinra's body is simply not damaged enough for what happened to him in the events of the game (to which this film is a sequel). He was in a building that was all but completely destroyed, and the room he was in was consumed with fire. Obviously one could survive such an ordeal, but to have almost no damage on his body (save the patch on his head) is impossible.
Corrected entry: During the fight scene at the Forgotten City, after the fighting begins, all of the children who were standing around in the previous scene disappear.
Correction: At the beginning of the fight, if you look in the background, you can see all of the children running away into the forest.
Corrected entry: In several of the shots in the movie, the CG animation of the character's lips doesn't match up with what the character is saying. This is due to localisation errors (change the language from Japanese to English)
Correction: This is not a mistake. Whether you're talking about animation, cartoon or live action, movies are dubbed to multiple languages all the time. To have lip movements sync up with all possible languages would be impossible. So lip movement mistakes are only valid for the original language of the movie.
Corrected entry: When Rufus jumps from the building, he pulls his gun out twice between shots.
Correction: Rufus only pulls out his gun once-as he's falling off the building.
Corrected entry: After Cloud uses his Omnislash attack to finish off Sephiroth/Kadaj, Cloud's various swords all land on the ground, within ten feet of him, forming a circle. Yet, when Kadaj lands on the ground, the swords are much further away, at least 20-30 feet away from Cloud.
Correction: If you pay attention closely, the various swords do create a sort of circle or elipse, however Cloud does not land in its center and as it appears some swords are further away and some are closer. When Kadaj falls, from the angle on Clouds left that you're looking towards Kadaj the swords do appear further, but that is only due the the angle of the shot, instead of birds eye, you now have a horizontal shot from further to a side. An illusion, rather than a mistake. Noting that in CGI is it more tedious to MOVE objects rather than to leave them remaining where they are for continuing scenes, thus errors of this sort are somewhat difficult since scenes are created in a flowing manner (one would hope).
Corrected entry: What happened to the flare that Cloud passed through to reach Bahamut? It was still flying towards the ground after Cloud passed through it, and after Bahamut is defeated there's no sign of the flare hitting the ground.
Correction: The flare actually dissipates when Bahamut dies; it has not hit the ground as it's falling slowly relative to Bahamut and Cloud. Cloud passes through it to slice Bahamut, who begins to disintegrate; anything left of the flare would be dispersed when Bahamut fell through it (as he falls you can see him surrounded by the blue flare energy).
Corrected entry: When Bahamut is summoned by Kadaj, he uses what looks like a green (magic) materia instead of the correct red (summon) materia.
Correction: Incorrect. In the original Japanese version the Summon Materia is green, not red. Red was used for Healing powers in the Japanese version. Since this is merely a dubbed Japanese movie, there was no reason for them to change to colors of Materia for us.
Corrected entry: After Sephiroth turns back into Kadaj when defeated by Cloud, Kadaj is carrying his weapon. However, Kadaj had lost this weapon before he turned into Sephiroth and Sephiroth's own weapon was created with him. Therefore Sephiroth's weapon couldn't transform into Kadaj's when Sephiroth is defeated.
Correction: When Kadaj is falling off the building with Jenova's head, after his sword falls, as he turns into Sephiroth watch closely; when Cloud attacks Sephiroth you see Kadaj's katana turning into Sephiroth's Masamune. So Sephiroth is technically using Kadaj's katana.
Correction: Differences between the game and a movie based on the game are not valid mistakes. The change or injuries to Rufus would have to be different within the movie itself.