There is the Toy Box which is full of minigames such as "Fortune Teller". It also has pictures which you can print out using the Game Boy Printer.
Glitches and bugs have been fixed, such as the "Minus World" glitch.
There is a mode of play called "You Vs. Boo" where you race against Boo in eight different stages.
There is a photo album were you can unlock pictures of things like Goombas and Mario and write a caption underneath. You could also print them out using the Game Boy Printer
Instead of the image being smaller, Mario and Luigi are bigger, and only part of the image is visible. But you can move up and down to see above and/or below Mario/Luigi, and use the select button to see to the left and right of Mario/Luigi.
As well as the original Super Mario Bros. game, there's also the Challenge mode, where you play the levels you unlocked freely, and try to get five Red Coins, one Yoshi Egg, and the high score.
All of the levels have been altered, including changing various enemies.