Bug: Spy: The Diamond Back has the ability to award crit shots for each backstab or building sapped by the Spy. However, a bug exists where even if backstabbing someone who is invulnerable, like ubercharged or under the influence of Atomic Bonk, will still award a crit shot despite not killing the person stabbed.
Bug: Any strange primary weapon for the Pyro can have the Strange Part: Underwater Kills added to it. However, the primary weapons for Pyro do not work under water, and any player ignited by the flamethrowers are instantly extinguished the moment they land in water, making it impossible to get any underwater kills with these weapons.
Bug: Scout/Engineer: The misc for the scout called Ball-Kicking Boots spawns a team colored soccer ball with the player that can be kicked around the field similarly to the TF2 birthday beach ball. This can not be destroyed by most things. However, the Short Circuit weapon for Engineer can destroy this as if it were a projectile.
Bug: So far, I have only found this glitch in Dust Bowl on the second capture point in stage 2. On the Red Team side, exiting the starting room, you see a folding down garage door that is always shut. Sometimes, it will be off set. The door is not connected right, and actually sticks out into to the walk way. Players can walk through it, and can't go in the door though due to an invisible wall.
Bug: Mann Vs. Machine: I have found that sometimes, when the wave is failed and the Machines successfully drop the bomb into Mann Co. a glitch happens that I have discovered with The Heavy. After a wave has failed, the Mann Co. Defenders team does the loser position where you can run around with hands in the air. But sometimes the Heavy will be completely invisible to the person playing him. Not sure what causes this, and so far only discovered with The Heavy.
Bug: Players are able to customize a tag which they can spray on most locations on the map. After a tag is sprayed, any player who looks at it gets a red text display saying SPRAYED BY and then says the person's name. If the player that sprayed the tag, then leaves the match, their tag will disappear. However, if any player looks at the spot where the tag was, they still get the text pop up saying there's a tag there and who it's sprayed by, only there's no tag.