What is a calling card?

DEFINITION OF A CALLING CARD : A calling card is a particular object sometimes left behind by a criminal at a scene of a crime, often as a way of taunting police or obliquely claiming responsibility

The Return of the Pink Panther is a detective film on a stolen Diamond which is called 'the pink panther'
In "Return," the fabled Pink Panther diamond is again stolen, with the Phantom's calling card monogrammed glove left as a clue.
In the Pink Panther films, each time the phantom steals something, he always leaves a white glove with the letter 'P' on it and it is a clue that he committed the crime.

*We have taken this idea, initially with the fairy wings but now with a scarf.

It is as though the character wants to be caught when she knowingly drops her scarf .

as we are doing a Psycho-Thriller, we found this useful as it really portrays the fact that whatever the character has done. She has done it purposely. This establishes her unstable mentality