Harry Potter and the Half-Blood Prince - Easter Eggs & Hidden Details

In the opening cafe scene, a poster behind Dumbledore advertises a perfume called 'Divine Magic,' subtly referencing the wizarding world bleeding into the Muggle one.

In the flashback to the orphanage, there are seven small stones lined up on young Tom Riddle's windowsill, foreshadowing the seven Horcruxes he would later create.

When Slughorn disguises himself as an armchair, his feet are briefly visible before he transforms back, a visual gag hinting at his imperfect concealment.

The cursed necklace that hurts Katie Bell is visible in the previous film (Chamber of Secrets) in a deleted scene (or background) at Borgin & Burkes, showing J.K. Rowling's long-term planning.

Draco is often seen using his wand as a walking stick or fidgeting with it like a cane, mimicking his father Lucius Malfoy's mannerisms, symbolizing his forced accelerated adulthood.