Pilotwings Resort [3DS]

Diamond class missions and vehicles
Get a "3 Star" rank on all missions in every class.

Meca Hawk Diorama
Get a "3 Star" rank on all Diamond class missions.

Free Flight collectibles
Reach the indicated class to unlock the corresponding collectible in Free

Flight mode.
Balloons: Silver Class.
Extras: Gold Class.

Free Flight vehicles
Complete the indicated task to unlock the corresponding vehicle.
Turbo Jet: Complete all Silver Class missions.
Cycle Glider: Complete all Gold Class missions
Super Rocket Belt: Complete all Platinum class missions.

Castle at Private Island
Collect all 75 Sight Rings in Free Flight mode.

Mario reference
During the "Three Minute Glide" mission, the sound of Mario dying can be heard when you fly through the small village.