Line of Sight Glitches are glitches that happen in the Arcade Custom and Mapmaker simply based on which way the player is looking. They typically involve Bots or Story AI, and how these behave whether or not the player can see them.
- Attacking Bots and Story AI cannot pass through doors unless the player is watching. They will run forever at the doorway until the player arrives (or operates a camera) to see them come through.
- Bots ignore the "one-wayness" of one-way teleports, and will go through the wrong way if the player isn't watching. If the player watches, however, a bot trying to use a "receive only" teleport for sending instead will be seen to run past the teleport to run against the nearest wall. If the player turns his back on the bot as it runs against the wall, the bot will disappear into the wall, on a B-line to the "send" teleport.
- A Deep Diver Story AI cannot aim with dual weapons normally, due to a strange lack of animations for him to dual wield weapons. He only gains the ability to shoot with dual weapons if the player is facing away from him.
- A bot running over a glitched (overlapped) large pit will not be killed unless the player is watching; when not watched, the bot will enter and exit the death area unharmed.
- On Gamecube, the assault compass will not appear in a mapmaker assault game unless the player sees the inside of a tile that is positioned in the map grid at the extreme northwest corner of the grid.
- Zombie Story AI will walk through windows, across death tiles, and across open gaps if they are shambling at the player and the player's back is turned.
- Zombie Story AI will walk up through the air out of a constructed pit if they are shambling at the player and the player's back is turned.
- Robot Story AI attacking the player will not walk forwards towards the player unless the player is watching; if the player's back is turned, Robots will stand forever in the same spot as they fire.
- Bots in free-for-alls fighting amongst themselves outside of the player's view will never be killed, and if bots are on opposing teams one team will sweep the other team at an unrealistic rate if the player is not around to see what is going on.
- In team modes, monkey bots cannot be killed by other bots at all unless the player is present to see the monkey get killed.
- Bots cannot transmit virus to one another unless the player is present to see the virus transmitted.
- Bots and Story AI can knock over an explosive barrel placed in their path, but only if watched by the player; if not watched, they will run through the barrel without touching it.
- Unarmed bots that have been shrunk are too short for the bot to punch the player, unless the player's back is turned, or if the player's gaze is fixed on another location via camera switch.
- Bots can kill each other with Flamethrower over infinite distance if the player is not looking.
- Bots will not throw grenades at you if you are not facing them.