My first QA job was working on the sequel to an original XBOX launch title, I was brought on for the last push before cert submission. The game was a 3rd person fantasy RPG which involved a lot of ranged spell casting. The player could also choose to do melee attacks, but since they melee combat was awful and mostly ineffectual, people avoided using it.
While playing through the game on the night before submission, I found a crash. One of the enemies in the game was an archer riding on the back of a giant frog. The archer would fire at the player, the player would fire back at the archer and usually kill it without much trouble. If the player wandered into melee range of the frog, (which nobody had done, since they had much more powerful spells,) it would raise up on its hind legs and swat at the player, resulting in a crash 100% of the time.
Solution? Delete the Frog/Archer units from the game. Other enemies were not added to compensate for the missing Frog/Archers, and I believe the Frog/Archers were left in the manual.