During Memory Block 6, when entering Arsuf to assassinate Robert de Sablé, there is a glitch that can occur if you ride through on horseback and have a second controller connected to the console. Once you reach the cliffside with three archers near the start of the area, after killing them, there is a chance that a second Altair spawns in and copies his every movement and action. They can lock on to each other, and in combat the two Altair's often target the same enemy. Any hit that either Altair takes will lower their health, including those that one Altair inflicted on the other. There cannot be more than two Altair's and the game attempting to focus on both of them can also lead to a number of other reported camera, cutscene and boundary glitches in the area. The most common method to obtain the second Altair involves continuing down the path on horseback where he will fall through the floor, die, and respawn with the second Altair. If you wish to get rid of the second Altair, simply disconnect the second controller from the console.

Assassin's Creed originally started as a Prince of Persia Spin-Off, "Prince of Persia: Assassins". It was going to follow the events of a young Prince's female bodyguard as she escorts him through Jerusalem. The game was also going to feature co-op. However the game was cancelled when Ubisoft heard the game was about the bodyguards and not the Prince himself.

During the game's opening, Altair is seen shooting a crossbow at an enemy. In the beta version of the game, the crossbow was a usable weapon, but was never made available in the final release of the game. The opening cinematic was very likely made during the beta period of development. The crossbow doesn't make an appearance until Assassins Creed Brotherhood.

On various buildings around the world, there is an arrangement of windows designed to look like the front of Optimus Prime in truck form.