Visible crew/equipment: At the end of the Quidditch match, when Ron shouts, "Woo hoo!" with his arms raised, just as his cape flaps around the black seat on the actor's broom becomes visible. There are a couple of other quick glimpses of a seat during the Quidditch match. (01:38:45)
Visible crew/equipment: When Slughorn stands before Tom Riddle speaking of seven Horcruxes, as the professor faces the fireplace and says, "This is all hypothetical," and when Tom replies, "It'll be our little secret," in these close-ups particularly the square lighting/reflector screen becomes clearly reflected in their eyes.
Visible crew/equipment: When Harry is lying outside the hut at the end of the film, Snape kicks his wand away. A block of neon tape can be seen briefly beneath the wand when Snape kicks it.
Chosen answer: Snape wants to know how Harry knew Sectum Sempra. As shown by him using Occumelancy to see where his copy of Advanced Potion making is. But at the same time, if Snape punished Harry for a spell in a book, Harry could show it to Dumbledore, who would recognise Snape's handwriting. Additionally, Harry was certainly punished in the book - he got detention with Snape every Saturday for the rest of the term. The movie most likely had to cut this for time issues, and also perhaps because the scene is more dramatic if Snape only silently glares at him.
Ssiscool ★