The number 5 constantly appears throughout the movie.
Jean-Paul Rouve resumed his role as David Rousseau in Polar Park (2023).
The song Martine/Candice sings is "I Wanna Be Loved By You". Debbie Reynolds sang this in the movie Three Little Words (1950) although in that movie, in spite of her excellent singing voice, she was dubbed by Helen Kane, the original Boop Boop a Doop girl.
The Helen Kane/Boop Boop a Doop connection is significant. An even more evident tie-in is that Marilyn Monroe sings this song in Some Like It Hot (1959).
The frequently appearing 5 figure is likely a reference to Chanel number 5 perfume. Marilyn Monroe famously said she only wore this perfume while in bed