• Mario can get around easier if he just crawls.
• You can get 5 coins by running around posts in 3 tight circles.
• You can run at some walls to climb them

GETTING INTO THE SECRET COURSES
                                       

• The Princess's Secret Slide:
  The Princess's Secret Slide is located on the top-right side of the Castle's first floor. You need at least 1 star to enter.
• The Secret Aquarium:
  Jump into the black opening that is to the right of the Course 3 entrance (the picture of the sunken ship). You need at least 3 stars to enter.
• Wing Mario Over the Rainbow:
  On the far-left side of the Castle's third floor. Go to the left of the giant clock and enter the large square opening in the wall, then drop into the hole. You need at least 50 stars to enter.

 STUFF THAT HAPPEN AFTER 120 STARS

• First a cannon will open up in front of the castle. Blast you self up to the roof and you'll meet Yoshi who'll give you a special message and 100 1up mushrooms
• Another thing that happens is that a HUGE penguin challenges you to a race at Cool, Cool Mountain.