Revealing mistake: Immediately after Jen dies in the hospital room, Grams wakes up and notices something is wrong. She stands up and checks Jen's pulse, using Jen's left wrist. You can see a clear small marking/line of some kind on Jen's wrist, and Grams slides her fingers directly over this mark to check the pulse. Apparently the mark was a cue for Grams to know where exactly to place her fingers in the scene.
Audio problem: During the narrative for the Season Finale, second half, Paul Stupin the Executive Producer is talking about Joey and Pacey's romance in the show. He mentions that they went on an "epic journey on a sailboat all over the world." He's a bit mistaken; as when Joey and Pacey went sailing at the end of Season 3, they sailed from Massachussetts down the Eastern Coast to Florida and back again. It was hardly "all over the world".
Audio problem: During the Season Finale Narrative, second half- Creator Kevin Williamson mentions that the kiss between Doug and Jack on the beach was "the second gay kiss in the show". He's a bit mistaken, as this was actually the 4th gay kiss in the entire series. Jack kissed Ethan in Season 3, Toby in Season 4, David in Season 6, and Doug in the Season Finale.