Secret exit Edit
On the movie set with the lunar landscape, walk towards what appears to be a model of a space shuttle. Press the "USA" sign, and the shuttle will open, revealing a secret exit to Tier Drops.
There are 4 secrets in this level. There is also a hidden entrance into secret level Tier Drops which is not marked as a secret place.
Secret #1: 3D Realms tribute
Right after you start the level and clear the outside of the enemies, jump on the dark grey wall where the helicopter crashed, then into the small shelf under the "Lunar Apocalypse" poster. Walk on that shelf then into the 3D Realms sign on it - you will appear in a little hidden room behind it, there is an Atomic Health. Then walk up the ramp, there might be an Assault Trooper if you triggered his spawn before. Also when you walk on the upper floor of this room, an Assault Commander will respawn on the outside, aimed right at you. You can collect there a Freezethrower and 2 ammos for devastator.
Secret #2: Snack machines
Go inside the cashier booth of the subway and press the cashbox on your right. Then jump out of the booth and run into the dark part of the subway entrance - on of the snack machines have opened, revealing a small place with two atomic healths. You have to hurry though, as you have very limited time before the vending machine rises back, covering the room again.
Secret #3: Jumping into the Earth
Inside the room with the artificial spacecraft, where the red Access Card is located, just jump into the wall in front of the spacecraft - you will find yourself inside a secret room that is part of the ventilation shaft. There is a shrinker and jetpack. You can also exit this room by flying up and opening a hidden passage into the rest of the ventilation shafts.
Secret #4: Dangerous boxes
Inside the magazine room, after the blue access card door, just walk to the tallest stack of boxes and open them - the highest boxes will be accessible, however there will be 1-3 Sentry Drones inside. After dealing with them, jump inside and collect a Devastator weapon. For easier access you can also use the jetpack which can be found in the previous secret.
- Duke's remark about this being the second time his ride was shot up is a reference to Hollywood holocaust; since he's remembering the first time the aliens shot up his ride too.
- A poster titled "Lunar Apocalypse starring Duke Nukem" can be seen in this level; it's a reference to Duke Nukem's exploits in space and the people at the studio appeared to be making a movie based on it. One of the movie sets in this level also appears to be a scene from the movie based on Lunar Apocalypse as Enforcer gibs can be seen around it.
- In Duke Nukem 64, the Tier Drops level is not present, and thus nor is the entrance to it. Instead there is a secret level entrance at the back area, which leads to Area 51 as a secret level.
- If you crouch-jump under the exit door at the start, you can get to the regular exit early and bypass all the enemies.