Throughout development of Shipwrecked 64, Squeaks D'Corgeh would make references to a non-existent character in the game named "Duncan Dolphin". This even included a fake death animation for a character named "Drake Dulfin" (likely intended to be the Spoiler:Starling counterpart of Duncan) being shot in the face by Spoiler:Brandon Lester in his Bucky Beaver costume in what appeared to be a Wild West-esque setting. This continued after the game's release, where one of the patch notes for the Hotfix 2 update stated "Removed Duncan Dolphin", likely as a reference to the "Removed Herobrine" gag seen in updates to Minecraft.

However, on April 1st, 2024, an April Fools update was released that added Duncan to the game as a New Game+ bonus. If the game's True Ending has been reached, he will appear in The Theater at Midnight and ask Bucky for help activating his "New. Radical. Mechanism!!" due to losing the trinkets needed to make it work. This will take the player to a new area called "Garten of Duncan", a recreation of the Testing Sector from Garten of Banban made using assets from The Plaza. Clearing the map will take the player to a previously unused location called "Layer 4 Elevator", where an audio tape reveals that the player can input console commands to access other unused locations as part of the update. Entering the door will take the player to another new area, known simply as "Sample Area", but only a few seconds after entering the player will be kicked out to the encounter with the Spoiler:Studiogrounds Husk at the end of the game.

Notably, in the "Layer 4 Elevator" area, Chief Wulf can be seen on top of the tallest building in the area. If the player uses console commands to reach him, he can be spoken to, revealing that Spoiler:he has relived the same days over and over again, watched Stumbler O'Hare die over and over as part of that, and believes that he will be forgotten after his death.