I dunno if its considered a bug or not since I am unfamiliar with Frontier tech, but:
In ep. 25, Sheryl changes holographic outfits on Battle Frontier into the purple one seen in the intro, as does Ranka on Macross Quarter. However, once they are on the planet, Ranka is back in her actual outfit that isn't holographic whereas Sheryl's still is wearing her holographic outfit.
Before Sheryl started singing in ep. 24, she was in a robe and parts of her purple outfit would have been showing is she was already wearing it under the holographic images.