I was rewatching the episodes when I noticed something. Twilight's cutie mark is is a purple 6 sided star surrounded by 5 white 6 sided stars. As seen here:
However, I noticed something odd during Magical Mystery Cure. When her cutie mark appears in the sky as she descends back to Poneville after receiving her wings, there is 6 white stars. There is also 6 stars on her banners when she enters the throne room.
I was wondering if anyone out there understood why this happened. I don't believe it was an error, but intentional. It is the purpose behind this that has me wondering.