Is it possible to have more than three saved games in Super Mario 3D Land

Well for starters, I would usually go look for the little nooks and crannies in a level, such as a wall which may have bricks you can break with a tanooki suit or by crouching under small holes that lead to rooms(Usually they are 1Ups but they can be paths to coins). Next EXPLORE as i would climb the walls of levels and follow the paths until something appears, and always use the binoculars, as you can spot out toad, and when you zoom up to him, he will toss a coin and you can collect it at the designated area. There may be more ways, but these helped me find the majority of all the coins. Hoped this helped!

To get StreetPass data, you just have to have the StreetPass feature turned on for the game. You can have up to 12 games turned on for receiving StreetPass data at one time. You don't need the system on, or the cartridge for that game in the system.

If you want to send StreetPass data to another game, you'll need that game in your 3DS. Therefore, people you pass who give you Super Mario 3D Land data have that game in their system.

A discussion in a thread on Nintendo's forums put it this way:

You do not need to have the game on or even inserted into the system to recieve Streetpass content for that game. The 3DS will recieve up to three Streetpass data transmissions per game at a time, which you can see in the Notifications tab on the 3DS home screen. However, in order to automatically send data transmissions for a game, you must have the game inserted but not necessarily on.