This is presumably a placeholder for all objects without an item graphic. Doing so will show a yellow-green colored image of an apple as the HUD icon. Notably, in Alpha 1, if the Neighbor breaks down a door, it can be picked up.
The player also has shorts with a golden apple design on them in the first two acts of the game. There also no longer appears to be a cutscene for the apple, and it instead grants the player an achievement. In the final build, the seed instead appears on the lone platform containing an armchair and a bear rug.The same tree is found as a sapling in the Beta 3 basement.
In Alpha 3, the player can find a supermarket known as "The Golden Apple." It has no collision data, and so is speculated to only be used in a cutscene.