Super Mario 64 on N64 - Level 15: Rainbow Ride - Coins and overview
Level Stars

Overview

1. There is a shortcut that lets you skip the first carpet, which is a bit long. At the start, turn around and do a long jump toward the pole.
2. There is a rather useless teleporter in front of the mansion entrance leading above the vertical maze, where there is a 1-Up.
3. The cannon is on the ship. The pink Bob-omb that opens it is at the top of the vertical maze.

The 8 Red Coins

The 8 red coins are all in the same area. Take the first magic carpet (or take the shortcut) and head straight ahead toward the big gray structure, which is actually a mini vertical maze containing the 8 coins. Note that the Start button lets you see quite a few coins with a somewhat global view.

Bonus Star: 100+ Coins

For the bonus star, I recommend starting with the vertical maze. Take the magic carpet and the 24 coins on the 4 "round" platforms you will pass. The idea is to try to collect the blue coins as quickly as possible, because there are 6 (30 coins) and you'll need to nail the wall jumps to get to the top in time. These coins aren't mandatory but make the task much easier. If you have extra lives, I recommend retrying the level if you happen to fail the challenge. I then recommend heading to the swings. By killing Shy Guys (a bit dangerous) and Lakitu, you should be able to reach 100 coins. If that's not the case, all that's left is to take the magic carpets leading to the top of the level to complete your collection. There are a lot of coins in this level (164, apparently), but that's fortunate since there are several paths.