Night Fall is the 3rd World of Ultra and Super Duper Mario Bros.. It is a World taking place at night, with night levels and such. The trees are white like in Super Mario Bros..
Level 3-1 - Night
The first night level as well as Night Fall's first level. There is a Fire Flower power-up and the level introduces Hammer Bros.. Ropes and small bodies of water are also featured in the level, and Venus Fire Traps are also re-featured. In all the whole level is an introduction to Night levels.
Level 3-2 - Night
The 2nd level of World 3 is another Night level. This one takes place outside of a sort of temple, and introduces Boomerang Bros., littered through the level (although there are no Hammer Bros.). The Glowing Baby Yoshi is again featured, as in some places (like inside the temple) there is utter darkness. Blokkabloks are re-featured from Level 2-S, and the last enemy introduced is Thwomps, inside the temple. (Also a Tail Thwomp). It also re-features Puppups and Kittkits.
Level 3-3 - Sky
A Sky level, but again taking place at night. The Blimp Baby Yoshi is featured after the checkpoint, and there are many platforms as well as Pirahna Plants. Bunny Goombas are found in lots of places and there is a secret pipe leading to a Star Coin in the water, with a Porcu-Puffer guarding it.
Level 3-4 - Tower
The Tower of World 3. There is rising lava in this Tower, with Dry Bones and Hammer Bros.. There is a Water Flower and metal grates, and at the very top Boom Boom is fought again, this time with two platforms that push Mario in either direction.
Level 3-5 - Ghost House
The first Ghost House featured in the game. It introduces Boos and Tail Boos, as well as Circling Boo Buddies. The Bunny Suit is hidden within the house, and there are tricky puzzles to get through. This level, after beaten, leads to a choice of two levels, 3-6 and 3-7.
Level 3-6 - Sky
Another Sky level at night. There are lots of Donut platforms and two Big Boos, one near the beginning an one at the end. This level takes place outside the Boo House, so the only enemies are generally Boos. The power-up is the Bunny Suit.
Level 3-7 - Sky
The sister level to 3-6, with the blocks that change to the beat from 3D Land. Wallops are back, but have a sort of different pattern since this is a 2-D game. Hammer Bros. and Boomerang Bros. are again featured as well as Balls on Chains. There is no set power-up so a Roulette Block is in the level.
Level 3-8 - Battleship
The first Battleship in the game, introducing Battleships to the Super Mario series. Battleships are like Airships exept in the water, with water in lots of places as well as the new water enemies for Battleships, Cheep-Chips. (Robotic Cheep-Cheeps). Deep-Chips (Robotic Deep-Cheeps) also are introduced. The boss at the end is the Koopa Mech, keeping with the under-water robot theme.
Level 3-S - Water
Another water level, half underwater and half on a bridge. In the water, Cheep-Cheep variates, Bloopers, and Spike Eels appear. Whirlpools appear that can suck Mario or another Bro. into a bottomless pit. In the bridge at the top there are leaping Cheep-Cheeps and Boomerang Bros.. Also the power-up is a new Baby Yoshi, the Skate Baby Yoshi, which lets Mario ice skate on a moving ice platform.