When you get to Agent One there will be a lever on the left. Pull it.
2001: A Space Odyssey reference
During the last quarter of the game, nearly all the sound effects for the radar equipment, assorted machines, generators, etc. are taken directly from Stanley Kubrick's classic film, 2001: A Space Odyssey. Pod Bay door effects, Pod radar beeps and alerts, and many other easily recognizable sounds are incorporated into the levels.
Airstrike in multi-player mode
A lieutenant can call in an airstrike by pressing Zoom, then pulling the trigger on where you want the bombs to drop. There is a ten second delay.
Aliens reference
The main menu music for the game has been taken directly from James Cameron's film, Aliens. If you own The Deluxe Edition CD of the movie's soundtrack, track 13 (Futile Escape) is the theme for the game's menu.
Beat The Uber Soldat
To beat the Uber Soldat, don't use the Venom machine gun, it is not very effective. Use any sniper rifle and just keep shooting at the solider. When you need to reload or need help, jump off the second floor thing onto the first with the Super Solider and go right where there is a table with health. You can hide there because the Super Solider won't go that far to find you. Then get a good angle and start shooting at the Uber Soldat until it's dead. When the Solider dies, be careful of the regular Nazi Soldiers.
Head shots
Turn off the automatic aim option to get a good head shot. Otherwise, you will lock on to the enemy's body.
Peeking around corners
Click and hold the Left Analog-stick while moving it left or right. The only problem is that you cannot shoot.
Wolfenstein 3D
Successfully complete single player campaign mode to unlock the original Wolfenstein 3D.