During the Credits
There are no extras during the credits of Super Mario Bros..
After the Credits
There is an extra scene where two Japanese businessmen are seen discussing a deal to make video games based on Iggy and Spike. Iggy suggests the game should be called ‘Iggy’s World’, while Spike says that the game should be called ‘The Indomitable Spike.’ They then both agree that the game should be called ‘The Super Koopa Cousins.’