I couldn't miss the chance to practice my drawing!
The Ninja Rage bug is a random bug in Final Fantasy VI involving the Ninja Rage that causes a formation error for Gau. Any party member that uses any scroll abilities (Flame Scroll, Water Scroll, and Lightning Scroll) (not the throwing items version), may or may not return to their original positions after use. The only way to achieve this without hacking is through the Ninja Rage, since it uses Water Scroll as an attack. This bug is not in reference to the actual scroll items that Shadow can Throw, but the enemy abilities that are used by Ninja and Covert.
This minor, harmless bug can be performed with Gau while he is using the Ninja's ability; normal attacks do not contribute to the formation error. Normally, when Gau uses a special ability he'll step forward, perform the ability (special abilities/enemy spell/magic spell), and then take a step back to his normal position. If this bug occurs when Gau uses the Ninja Rage, he'll take a step forward, and use the Water Scroll ability, but he will not take a step back after using the ability. By using the ability again, he will step forward and once again not take a step back. This can be done multiple times, until Gau is on the other side of the battle screen, opposite from the rest of the party. He will then turn around to attack the enemy, and move back towards the party with the next ability cast. Before reaching the party's side, however, he will turn to face the enemy again to attack it, and it remains in this loop (where Gau's sprite will always be near the enemy, going back and forth) until the enemies are killed; if he is KO'd, the fallen sprite will remain where he was. It is only a visual bug and does not affect gameplay.