7 Grand Dad is a rather infamous bootleg hack of The Flintstones: The Rescue of Dino and Hoppy where Fred Flintstone's in-game sprite was edited to look like Mario. All of the unused content from the original game can still be found here.

Unseen Title Screen Graphics

Present in the CHR ROM is an unused row of tiles for the Mario lookalike on the title screen (taken and modified from Dian Shi Ma Li). Above is a mockup of what it would look like if it were displayed correctly.

Level Select

A surprisingly overlooked level select can be found by pressing Select on the title screen. It causes the number in the "copyright" text to go up by one until wrapping around after 5. This has an effect on the level order on the map screen. This cheat was not present in the original game.