- "Duke-Burger" redirects here. For other uses, see Duke Burger (disambiguation).
Secret 1: Above the drive-through window
The first secret is outside the restaurant, above the drive-through window. There are two ways to reach this secret.
The first way to reach this secret is from outside the restaurant. On the outer edge of the cement column that separates the drive-through lane from the main street, there is an invisible opening about two-thirds up the column. The opening can be reached by jumping in a straight line from the barrel on the opposite side of the street, or it can be reached by jumping from the nearby cement wall and changing directions while mid-air. It can also be reached using the Jetpack.
The second way to reach this secret is from inside the kitchen. There is an invisible opening near the ceiling in the wall above the light switch in the kitchen. It is possible to reach this opening by jumping diagonally from the counter-top beneath the misspelled "Employies (sic) Must Wash Hands!" sign.
Secret 2: Desk switch
Inside the office past the kitchen, there is a switch on the backside of the desk with the Red Access Card. Activating the switch will temporarily open a compartment above the stack of boxes in the adjacent corner. This secret is unlocked by reaching the compartment before it closes.
Secret 3: Light switch in the slaughtering room
In the slaughtering room with the dog anatomy poster, there is a light switch beside the opening that leads to the conveyor belts below. Flipping this switch reveals a hidden door; the adjacent corner of the room will rotate. Following the rotating walls will lead to a hidden control room with an RPG inside. It is easy to become accidentally squished in the doorway, so caution is warranted.
Secret 4: Dog kennel
The fourth secret is inside the dog kennel. Go to the side of the kennel that has a dog in one of the cages, and use explosives to blast through the door of the top-left cage. The back wall inside this cage can be opened to reveal a secret compartment with Pipe Bombs inside.
- The rotating sign near the entrance of the restaurant says, "Duke Burger - 0 Burgers Sold." This is a parody of an old McDonald's gimmick that involved advertising the number of burgers sold in their restaurants.
- In the dog kennel, one of the cages is labeled "Scrappy Due" and contains a puppy, which can be killed. This is a reference to Scrappy-Doo from the Scooby-Doo cartoon series.
- The Society for the Preparation of Canine Hamburger (SPCH) is a parody of the real-life Society for the Prevention of Cruelty to Animals (SPCA).
- Pressing the "use" button while facing the microphone beneath the drive-through menu will trigger a voice that says, "Go away. We're, like, closed." This is a reference to the Beavis & Butt-Head episode "Customers Suck," in which Butt-Head tells off a customer at Burger World.
- Beside the deep fryer in the kitchen, there is a can of worms on the counter-top. This is a reference to the Beavis & Butt-Head episode "Closing Time," which features a scene in which the comedic duo places worms into the deep fryer and later tricks the health inspector into consuming them.
- Although the name of the restaurant on this level is always written as "Duke Burger," the name of the level itself is always hyphenated as "Duke-Burger" on the loading screen and in official game documents.
- Using the no-clip cheat to pass through the windows beside the front entrance of the SPCH building reveals that there are 2D sprites of metal bars hidden inside the windows. The metal bars are completely covered by the 2D window textures, such that they cannot be seen without using the no-clip cheat. This suggests the windows may have originally been planned to be transparent with metal bars preventing the player from passing through the windows.
- Duke-Burger also appears as a secret level in Duke Nukem 64. The secret entrance to Duke-Burger is found on Red Light District, which has been renamed "Gun Crazy." The Nintendo 64 version has been significantly modified and expanded. (See here for an illustrated summary of changes from Duke Nukem 3D)
- Duke Nukem Advance features a Duke Burger restaurant on the second level of Sydney. It loosely resembles the same restaurant from Duke Nukem 3D.