List of Luigi sightings in New Super Luigi U

In every course of New Super Luigi U is a picture of Luigi hidden, whether it be a sprite, a image in a wall, or otherwise.

7-3 Rainbow Skywalk

 * In the secret area before the end of the level, a large jumping 8-bit Luigi can be seen.

7-Ghost House Vanishing Ghost House

 * If the player takes the secret exit route, they will see a picture of King Boo and Luigi, which references their artwork from Luigi's Mansion: Dark Moon.

7-5 Flame Chomp Ferris Wheel

 * A cloud resembling Luigi can be seen in the background.

8-1 Magma Moat

 * There is a statue of Luigi taking off his hat at the secret flagpole.

The Final Battle

 * Luigi's face can be seen on the middle rivet of a platform.