Team Fortress 2/Leftover Assets
This is a sub-page of Team Fortress 2.
Half-Life 2 Leftovers
Over 2 gigabytes of Half-Life 2 assets can be found in the files, including voice lines, textures, closed captions, and many other things. The main reason for these files being included at all are due to several older maps using Half-Life 2 textures for lighting and smaller details. The game will also use them as "back up" files if certain Team Fortress 2 files are missing or deleted, such as the shotgun and rocket sounds. Most of these files are not actually needed to keep the game running (deleting all of the vo_english VPKs seems to have no consequences in particular), but there are a select few that will crash the game on launch if missing, namely hl2_misc_000.vpk and hl2_textures_000.vpk. Deleting all of these will result in some missing textures and most animations being completely broken, however.
Team Fortress Classic Leftovers
The model and texture files for the spawn room turrets from Team Fortress Classic (originally used in Half-Life) can actually be found within the game's files, unedited.
There are textures for the TFC teleporters in the files as well. They were likely used in place of the current teleporters for testing purposes, or simply just leftovers that were never used at all.
Main Menu Background
The main menu background from Team Fortress Classic is in the game files as intro.vtf.
Assault Cannon/Minigun Textures
The textures for the TFC Minigun/Assault Cannon can be found under materials\models\weapons\v_minigun.
The textures for TFC's viewmodel hands can be found under materials\models\weapons\v_rocketlauncher. The base texture is also present in Half-Life: Source.
Rocket Launcher Texture
The TFC/Half-Life rocket launcher texture can be found under materials\models\weapons\w_rocketlauncher and the rocket projectile's textures under materials\models\weapons\v_rocketlauncher.