A Glitch, also known as a Bug, is an error in the game that produces an effect that was unintended by its developers.
Glitches often arise from mistakes or errors in the game's code which go unnoticed during development and testing of the game. Glitches may cause problems to the player, but some glitches may be used to the player's advantage. Some glitches are more prominent than others, and some can be specific to a certain console.
Accessing Joey's Garage
The player can access Joey's Garage and see the whole interior as seen in cutscenes by performing the following actions. If the player drives a car into Joey's left garage door, gets out, and runs at the left corner between the door and the garage, they will clip into the garage. This glitch doesn't work in the PC version of the game.
One of the most well-known glitches is nicknamed "Blue Hell", and is also referred to as out of bounds (OOB). It is possible to leave bounds in every game in the series since GTA III. Once the player goes out of bounds and enters Blue Hell, they will fall for several seconds before returning to the surface, unharmed.
Broken Import/Export Crane
If the player dies while a vehicle is being transferred to the boat by the Import/Export cranes in Portland or Shoreside Vale, the crane may become stuck in the position it was in when the player died, rendering it permanently unusable, making 100% completion impossible without loading a save.
If a car explodes inside of a garage, or if the husk of an exploded car is pushed into a garage, walking away from the garage to close the garage door then walking towards the garage to open it will reveal that the car has been repaired, good as new. The reason this works is that when a garage is closed with a vehicle inside of it, the vehicle will despawn, and a fresh copy of the vehicle respawns when the garage door is opened. The game doesn't record the state of the vehicle when it is driven into the garage, only its model and color. This exploit exists in almost all 3D universe games.
Claude's "Killer Look"
When on foot, if there is anybody trapped under a car and the player uses the first person view, they will die instantly. The death will not be added to the player's stats. This also happens if the pedestrian is trapped under the car and the player starts a mission. This glitch is not present on the iOS version of the game.
Easy Vigilante Exploit
While performing a Vigilante mission, the player can get close to the target's car, pause the game, and then enter the menu screen. Once gameplay resumes, the criminal in the car will stop make their "getaway" on foot, being much easier to kill. Also, they will most likely shoot at other pedestrians if the player is not his nearest target. If this does not work the first time, just try again and get a bit closer.
This glitch allows the player's vehicle to go through solid objects (buildings, the blocked parts of the tunnel, etc.). To activate the glitch, the player must have another person with them in their vehicle; missions like Drive Misty For Me, Bomb Da Base: Act II, Kanbu Bust Out, Liberator, Marked Man. and Rumble are suitable. After this is done, they need to head to the crusher in Harwood. Park the car sideways next to the crusher and make sure that the driver's side is on the left, touching the crusher. Then, quickly get out of the car and continue pressing the button to enter the car. This will make the passenger get into the vehicle while the crane is picking it up. The player will then pull the passenger out of their vehicle, making the crane drop it. This makes the vehicle a "ghost car". To use it freely, the player must fail the mission by killing or abandoning the passenger. The only way to turn the ghost car back to normal is to store it in a garage. Not doing this will make the ghost car stay unsolid and make the player unable to enter it again. Another disadvantage is that it will increase in size the more it is driven.
Incorrect Vehicle Spawning
The 10th Anniversary iOS port of GTA III is notable for containing many car spawn glitches and other abnormalities. Occasionally, vehicles in traffic may spawn floating in mid-air before falling to the ground. Cars may also spawn incorrectly inside the Porter Tunnel, becoming stuck inside the walls of the tunnel or clipping into the road.
Missing Purple Nines
If the player starts a new game on a memory card with the mission Rumble completed, the Purple Nines, who are wiped out in that mission, will not spawn in the new game due to a programming oversight. This will make it impossible to complete Uzi Money and subsequent D-Ice missions, as killing Purple Nines gang members is the objective of these missions.
If the player manages to park three vehicles in a two-vehicle garage, the garage door will not close, and the sound of the garage door will play repeatedly to comedic effect. This glitch can be done easily with the oversized garage of the Staunton Island Safehouse by driving one car into the garage, parking another car halfway inside the garage to prevent the door from closing, driving a third vehicle into the garage, then driving the second vehicle the rest of the way in.
Porter Tunnel Skip
One method of reaching Staunton Island and Shoreside Vale before they are unlocked, without cheats, is by exploiting a glitch that allows the player to walk above the Porter Tunnel. To do this, one must drive a car to the concrete sea wall above the tunnel entrance on Portland Island. The player then parks the car right along the edge of the wall, in line with the tunnel. When the player exits the vehicle, they will fall through the sea and into Blue Hell, landing "on top" of the tunnel. The player can then walk along the tunnel, then jump into Blue Hell at the Staunton Island or Shoreside Vale end. The game will teleport the player back in bounds in Staunton Island or Shoreside Vale. If the player is busted or wasted after performing this skip, they will be brought back to a hospital or police station on the last island they unlocked.
Rhino Spawn Glitch
Rarely, when a pedestrian is killed, they may drop a large sum of money in total of at least $3,000. This may be a bug in the money drop rate, as this glitch can involve almost any pedestrian in the game.
Subway Tunnel Skip
This glitch is similar to the previous sequence break. It can be performed at the subway in Shoreside Vale at the airport. When the train arrives at the platform, the player can enter and then quickly exit the very last door of the train. Claude will teleport above the platform and will be standing above Blue Hell, and the player will be able to see the tunnel. The player can run "on top" of the tunnel, so long as they jump over any ceiling props that would pull the player back in bounds. The player then jumps into Blue Hell at the other end of the tunnel, the game will teleport them to Shoreside Vale. Getting busted or wasted here will deliver the player to the last island they unlocked in the story.
Taxi Driver Glitch
The player can perform the Taxi side-mission in any car by executing this glitch. This exploit relies on the fact that in GTA 3, side missions start when the side mission key is depressed instead of when it is initially pressed. If the player enters a taxi cab, and holds down the side mission button without releasing it, they can then enter any car they like. When the key is released, the taxi mission starts as normal, only now doable in the car the player is currently occupying. This doesn't work on vehicles that have side missions associated with them, however, such as police cars or fire trucks. This exploit is not present on the iOS port of the game.
Inside the tunnel that runs beneath St. Marks, linking Portland Docks with the Harwood Train Yard, there are four bum pedestrians that spawn in a circle around a Hidden Package. If the player drives a Bobcat into the tunnel and stops within view of the bums, gets out of the Bobcat, jump on its hood, and walks up to its roof, then the four bums will start walking around aimlessly. If the player then walks back down onto the Bobcat's hood, four more bums will spawn in the tunnel. The bums will spawn as many times as the player repeats this action, until the game reaches the limits of its memory and freezes after around 40 bums have spawned. In the PS3 version, the game will not freeze no matter how many bums spawn. This is a useful exploit, because the bums drop Molotov Cocktails, meaning the player can have an almost unlimited supply. This glitch has been fixed in the IOS version, however, as performing this glitch now merely respawns the existing pedestrians, rather than spawn extra ones.
Rarely, the player may encounter a different breed of police officer. Instead of running to the player's car as normal, an Ultracop will quickly float towards or teleport at the player's car door and pull them out, busting them instantly. The formidable Ultracop is also present in GTA Vice City. The name was invented and popularized by the GTA speedrunning community.
Vehicle Challenge Timer Exploit
During any one of the four vehicle missions (Patriot Playground, A Ride in the Park, Multistorey Mayhem or Gripped!,) the player can drive through a checkpoint just as or just after the timer reaches zero seconds. This may cause the timer to disappear and allow the player to take as much time as they like to complete the challenge. This is a useful exploit due to the considerable difficulty of these challenges.
By abusing cheats when the player steals a car, the player can drive destroyed cars. While stealing a car, entering the "blow up all cars" cheat and the "heal" cheat in quick succession will allow the player to drive the car's husk. This exploit is possible in GTA Vice City and GTA San Andreas as well.