Before you start this glitch, obtain all the red coins EXCEPT the first red coin at the entrance (false entrances, or falling does not matter from this point). Then after you get the other 7 red coins in this stage, get the last red coin located at the enterance. Continue on the path to the location of the star. DO NOT FALL, DO NOT GO INTO ANY FALSE ENTRANCES FROM THIS POINT, OR THIS WILL NOT WORK.
When you reach the red coin star point, 2 stars should appear there together, instead of 1.
NOTE: Because it's only a glitch star, both stars together count as 1 whole star. Once you get this star, the 2nd glitch star will not count towards your star total.