Gameplay-specific glitches
Reference Pose (Civilian) - A glitch which causes the player to appear to have no weapons in on their world model, and causes their model to enter a reference pose.
Taunting On Round End - A glitch which, upon losing a round, causes all extra models for taunts such as weapons, the box For The (Box Trot), Grenade and Scotch for (Spent Well Spirits), etc. to be invisible/missing. This is similar to the viewing of certain taunts on the loadout screen.
Inconsistency bugs
Building Damaged Model - Occasionally, after repairing a building, it will still emit smoke and small electric sparks implying that it is still damaged, despite the Sentry Gun being at full health. This can be fixed by redeploying the building. (Partially fixed)
Invisible Models - This glitch occurs on the PC version if the Alt+Tab shortcut is used while in full screen mode. Upon returning to the game weapon fire can be seen but the player's or weapons' models cannot. This usually happens on a random player with the rest of the players still being visible.
On PC, these bugs can be fixed by typing record demo; stop into the console.
Taunting While Dead - If a player dies immediately before a taunt dialogue line begins, their character will still say the taunt and even lip-sync while dead. (Happens frequently when taunting with the Bat or Minigun)
Taunt Loop - If a Sniper does the Huntsman Taunt to another Sniper equipped with the Huntsman, the enemy Sniper can counter with his own Arrow Taunt, even when stunned. It is possible to chain this infinitely until a third party intervenes or one of the two decides to end it. The same thing can also happen with a pair of Engineers using the Gunslinger's taunt stun, and a pair of Medics using the Ubersaw.
The Wrenchslinger - Occasionally, while a player has the Wrench equipped, it shows the Wrench being held by the Gunslinger. The method to do this is by equipping the Gunslinger, going to the resupply locker, changing to your Wrench, and going to the resupply locker once again.
The Safety Glove Slinger - Similar to "The Wrenchslinger", sometimes the Engineer's hand will look like a regular safety glove even though he is equipped with the Gunslinger. This may occur if the player is currently having lag. For some users, using the in-game overlay and searching something or watching a video will produce him/her the lagging. Whilst taunting with the Gunslinger the player will appear to have a robotic hand equipped.
A BLU Engineer demonstrating the Safety Glove Slinger
Blinking Hats - Occasionally other player's hats will appear to "blink" from pure white to black in-game. The glitch stops upon re-joining or map change.
Custom Model Glitch - Custom models for weapons and players can fail to appear, or appear in a Wireframe state, if the player enters a server with SV_Pure set to 1, instead of the default model loading. This error will continue to manifest until the player restarts TF2, even if they enter a server with SV_Pure set to 0. SV_Pure 2 servers do not cause this bug.
Spy's Third Arm Glitch - When a player reloads his Revolver and quickly equips the Dead Ringer or any other form of cloaking device, a second left arm will be reloading the Revolver, while the first is holding the Dead Ringer. The glitch occurs when a player has their viewmodel_fov higher than 65. Another example is when the Spy is holding the Dead Ringer out with a weapon other than the default Sapper out, (say, the Knife) and switches to the Sapper. The Spy's left arm is holding the Dead Ringer, but a second left arm appears to turn on the Sapper. Also can happen when the player has equipped the Sharp Dresser and the Dead Ringer and the player has the viewmodel_fov higher than normal.
Wrong Team HUD - Occasionally being automatically balanced to the other team results in parts of the HUD being the wrong team color.[1]
This bug can be fixed by typing hud_reloadscheme into the console.
Floating Critical Hits/Flame Effect - Sometimes the critical hit or flame effect will appear out of nowhere and float for sometime during gameplay.
Misplaced Laser Position - When guiding a Sentry Gun with a Wrangler, there may be moments where the laser beam will be misplaced but will still point to the target.
Incorrect Disguise Weapon Glitch - This glitch is caused when a Spy who is alone in a game disguises as a Heavy and switches his disguise weapon to fists. After this, if the Spy changes his disguise to the Engineer class, the Engineer's active weapon will still be shown as fists. This may or may not work with other classes or weapons.
Taunt While Moving - If a player taunts just before running off a ledge (using the imminent slowdown as leverage to fall), they will see themselves taunt briefly before falling off the ledge, where they will return to full first-person control. To everybody else, however, they will still be doing the taunt animation even if the player is moving around. This glitch also works with the Action item taunts.
Inability to lose on Mann Vs. Machine - It is possible that when the bomb detonates the game will continue without forcing a loss. The pit will appear exploded so when players from either team walk onto it they will die. This may only happen if there are only two to five players on the server.
Infinite Reloading - If a player playing on the winning team is reloading their primary weapon when Humiliation ends, then when they respawn in the next round they will keep going through the reload animation until the player uses primary fire.
Reloading while shooting - It is possible to reload while shooting, if the current weapon's magazine is not empty.
Infinite Market Gardener Crit - If a player rocket jumps just between 0 to 1 sec of the waiting for players countdown, when the round starts the player's Market Gardener will crit until they die, rocket jump or hold the Rocket Launcher for too long.
Wrong Health Hud - This bug occurs when using a custom hud, in which when a player dies, respawns with his health indicator stating he is at critical health. This can be fixed by typing hud_reloadscheme into the console.
Cosmetics Floating - This bug occurs when there are lots of custom cosmetics and/or lag that can cause classes to appear "hatless" but still show they have cosemtics that will show if you view their items. Somewhere else their cosmetics will appear floating in a somewhat civilian pose order.
Smoke coming from an invisible Spy - Sometimes, when an Spy is holding an Spycicle there can be "smoke" seen coming off of it, even though he is invisible.
Vote-screen crash - If you open up the vote screen during the Killcam, as the camera is zooming into the person who killed you, the vote screen will remain as a static image on screen. This prevents the player from closing it and doing basically anything except moving side to side. Forcing the TF2 client to shutdown is the only fix.
Weapons not visible for other class than Spy- Sometimes if you look at another player their weapons aren't visible. Maybe the game just didn't keep up.
Glitches caused by lag compensation
Sliding characters - Some characters will assume a default position (standing still) and slide instead of playing their running animation. This also frequently occurs as a result of pausing (with server cvar sv_pausable 1).
Fire effects glitch - Sometimes due to latency issues/lag, a player will fire their weapon, release the primary fire key, and still have fire effects emitting from their weapon, although it has no effect.
Mouse sliding - Occasionally, a user who was recently experiencing a lot of lag will find their movement keys no longer control their character, and the character is instead controlled by mouse movements. This is caused by the +mousemove command and can be resolved by entering -mousemove in console or by pressing a key bound to +mousemove (the Alt key by default).
Source engine glitches
On occasion, using the Alt+Tab sho