When Angela is trying out for the derby team, she is wearing the jammer skin on her helmet (the star). It cuts away from her, and then back and the jammer skin is gone, and then cuts away and back and it is back on her helmet.
When Angela is auditioning for the Derby Dolls, her helmet goes from a hard light blue plastic that says "Smackey Kennedy" to darker blue soft cover with pink star. This switch happens a few times through out this scene.