Continuity mistake: In Fred and George's joke shop Ron asks how much something is, the twins reply 5 galleons, one of the twins (closest to Ron) is leaning against the banister then in the next shot of him he is in a different position.
Continuity mistake: In the Christmas scene at the Burrow, while Harry, Lupin, Tonks, and Mr Weasley are talking about Snape: notice the trays of candies/baked goods on the table. When they are done talking and Ginny comes to sit down and give Harry a bite, a spot on the table has suddenly cleared for her to sit down her tray when Ron comes to sit in the middle of Harry and Ginny.
Continuity mistake: When Death Eaters reach Diagon Alley, there's not many people there; but after they crash there with Ollivander, the alley gets pretty crowded immediately.
Continuity mistake: When Ron sits down with Harry and Hermione in the Great Hall before Quidditch, the bowl/spoon is either right beside Hermione's left hand or farther away, depending on camera angle.
Continuity mistake: In Potions class, just before the students go to their cauldrons to prepare their Draught of Living Death, Hermione stands in front of Harry, but in the long shot she is instantly beside him, then she's suddenly back in front of Harry again.
Answer: The purpose of the Pensieve is to preserve the memory exactly as it was recorded. Telling Harry something years after an event occurred is not as effective or as accurate as seeing. It is more impactful if Harry can watch events exactly as they unfolded. Regarding Slughorn, he had refused to give his complete memory because he was ashamed of the unintentional part he played in Voldemort's plan to create the Horcruxes. He was duped by Riddle, but he still did not want anyone to know how foolish he was.
raywest ★