The ripped photo used as a clue appears in two versions from the first time it's discovered. The first version shows Sapphire laughing as she dances, with her mouth open. The second shows her smiling broadly with her jaw closed. It's quite an odd, unnecessary blunder in a police procedural.
As the detectives on the street approach the pub where the students gather, trad jazz apparently coming from the pub is heard, but the moment the detectives are inside the music disappears rather than growing louder.
Sapphire was a student at the Royal Academy of Music.
At 30:30 Superintendent Hazard refers to it as the Royal College of Music, a separate institution.