There is an unused graphic in the game's memory that says "Cheat On!". It is loaded in with the graphics of the first level.
Within the game's code are conversations between Bart and Lisa that go unused. This could suggest that it was originally intended for there to have been cutscenes that played between levels, but the idea was dropped during development.
The text "TOAST!" is loaded into the console's RAM in the SNES version of the game for every level, but there's no explanation for why.