Harry Osborn's butler suddenly telling him two movies two late the truth about his father's death absolutely should be on the list. It didn't help that the old timer playing the butler (Bill Paxton's dad) isn't exactly Michael Caine (who also played a butler in a comic book movie, Alfred Pennyworth in Christopher Nolan's Batman films). If you've ever watched the DVD extras, the poor guy has trouble remembering his lines.
Suddenly making Flint Marko responsible for Uncle Ben's murder would've been on my list too. First of all, it was a contrived way to give Flint a personal connection to Peter. It also undermined the "with great power comes great responsibility" message since Sandman went off uncaptured (and presumably still stealing for his sick daughter) at the end.
I don't agree with Doug's sentiments that the Spider-Man movies necessarily have to be really serious and non-goofy. Spider-Man isn't a typically "dark and edgy" hero like Batman, Wolverine, Frank Miller's Daredevil, or the Punisher. Yes, there are "serious" moments like the death of Peter Parker's uncle (the catalyst for him becoming a superhero in the first place) and Doug seems to forgot that Spidey loves to quip and trash talk. It seems like negative feelings steaming from Joel Schumacher's Batman & Robin has given certain folks the impression that the only way that a comic book movie can be good is if it's totally straight and hard-edged.
My main problem with Venom wasn't that he wasn't in the movie long enough per se, is that they probably should've saved him for another movie. As a matter of fact, Sam Raimi himself didn't want to use the character in the first place. A long-standing rumor was that Vulture (played by Sir Ben Kingsley) would've been in Venom's place. However, the powers that be at Sony pressured Raimi to include Venom due to fanboy pressure.
Why didn't Doug say anything about the lazy and awfully coincidental (there are a lot of coincidences in Spider-Man 3 by the way) way that the symbiote gets in contact with Peter in the very first place? I do agree with him that John Jameson would've been a more logical choice to ultimately become Venom (he has a legitimate beef with Peter because Mary Jane dumped him at the alter for Peter; they could use the animated interpretation of him getting in contact with the symbiote in space, etc.) than the Eddie Brock that we saw here.