After the fire drill, we see Delancy in her modified, purple uniform. However, as the group moves into the school, she is suddenly wearing the normal uniform and continues to until they arrive in the trio's room till it changes back.
After the trio is accused of stealing and are walked back to their room for an evidence check, the backpack is gone from Hadley's back. It reappears soon after she enters the room.
The plural of 'lady royal' should be 'ladies royal', not 'lady royals'