The glitch renders anything held in the left hand invisible, allowing 47 to hold large and unconcealable weapons, such as the SP12 Shotgun without having his disguise compromised. It is performed by having a large weapon holstered and holding the detonator.
Guards who frisk the player will still detect the weapon. However, if the player surrenders the weapon, the guards will not take it away.
People walking through doors glitch
On many of the Hitman games, people walk through doors. It seems to happen in You Better Watch Out… the most. Sometimes, the hidden target (?) will walk through a door and after you kill her, all the guards do the same and then the door won't and cannot close. You can also stand inside people, by crouching down then standing up, which can put you inside another person.
Fiber wire glitch
This glitch occurs randomly. Sometimes, if you try to strangle an enemy as they are turning round, or as they notice you, you will continue the strangling animation and they will begin to attack you. When the animation is completed, they will stop attacking and simply die on the spot. Be careful though, as they will alert other guards.
Another way to get this glitch is to headbutt someone, then run behind them and strangle them, doing this will cause them to repeatedly punch you until they fall over.
Sometimes you will also encounter that instead of strangle an NPC, 47 just quickly stretches the Fibre wire, and silently instant kills the NPC.
If you are holding a hostage and select a weapon though the number keys, you can pull out other weapons such as an SMG or you could pull out a coin, but the guards will still shoot you regardless of how stupid you look. When changing weapons, occasionally you will get the glitch where your arms are inside your torso and you walk without moving your legs. If you time it just right, you can take someone hostage while throwing away your gun, which looks creepy.
Human Shield Glitch
Since Hitman Blood Money, 47 can Human Shield a NPC, in order to use the character for protection in direct gun-fights or to knock him/her out. Sometimes, while you try to human shield a sitting character (for example, he is sitting on the couch), you might be able to do that, by sneaking behind him and pressing the "E" button. 47 will magically "withdraw" him through the couch, and the NPC will appear as a human shield. Attention: this will not work on all the couches/chairs, only a few are bugged.
Stun Gun Glitch
In Flatline when you are in the morgue, use the stun gun on Agent Smith while you are crouched and after you use the stun gun on him, he will be awake and crouched but you still have the option to sedate him, after you sedate him this will not work and he is still crouched on the bed, sedate him again, but this time Agent Smith will disappear and the bed too, and the game will freeze. Note that this has only been proven to work on the Xbox version.
This is a useful AI glitch to exploit if you're spotted by guards trespassing and need to get them off your back without leaving the area.
If a guard spots you trespassing from afar, he will run towards you. While he's doing that, hide behind something (such as a door) before he gets close. If done correctly, once the guard gets to your position, he will stand there like an idiot and leave after a few moments. Note that this will not work if the guard has already given the "stop gesture" to you.
Human Shield Method
This will only work if you are being pursued by just one guard and nobody else is around. This method involves simply walking behind said guard, and quickly pulling out a pistol and using him as a human shield, before knocking him out. If done successfully, the guard will not become a witness, as he is unable to see 47's face when held as a human shield. This is not easy, as there's a chance the guard will turn around and catch you in the act.
This is best done if multiple guards are chasing you. To do this, stay out of sight of the guards (hide behind a closed door), and shoot an unsilenced weapon. All guards nearby will enter "panic mode" and run towards the source of the noise, completely forgetting about you in the process. Take care not to get seen immediately after shooting, as this will provoke them into attacking you.
Pushing someone in a descending elevator will kill them. NPCs killed this way will be counted as an accident. If the elevator is stationary or ascending, they will simply get knocked out.
Additionally, dropping down from the elevator hatch while the elevator is going down will injure the player.
Mark Parchezzi stops running glitch.
Some rare times, when you have to chase Mark Parchezzi through the office and to the roof on The White House, he will stop inside the office and just look around. After a while, he will then start shoot 47 or continue running up to the roof. This glitch makes it easier to kill Parchezzi and also spares you from chasing him.
Oddly enough, if you're disguised as a worker, you can kill an NPC in front of everyone by throwing a hammer at their head and no one will know you did it. However, if thrown at any other parts of their body, they will survive the encounter and alert the guards about you (if the NPC is a civilian) or attack you (if the NPC is a guard).
Rat blood glitch
Strangely, if the player kills a rat, it will leave a large pool of blood on the floor, similar to that of a dead body of an NPC.
When the player is disarming a guard, there's a chance their firearm will accidentally go off. Strangely enough, this does not use up any ammo whatsoever, nor does it leave any bullet holes. For example, if the player snatches an SLP .40 pistol from a guard who hasn't opened fire yet, the player will always receive a fully loaded SLP .40 with 12 rounds, regardless of whether it discharged during the struggle or not.
This glitch is mostly only exploited by experienced players. The basic idea of this glitch is that, while 47 is in his original suit, his cover can never be blown. This glitch allows the player to run through guarded entrances or trespass as much as they want (and even get shot at because of it), and still get away with a Silent Assassin rating.