All-things-movie blog Cinematical pointed to this fun list of the films from 2005 with the most "goofs" (continuity mistakes, "plot holes", etc). SWETRS One-hundred and Thirty Nine mistakes in total, according to the folks at Movie Mistakes. It's a running list including contributions by visitors to the site, so the tally changes, and more recent or less popular films are going to be lower (for now) cuz they've had less scrutiny. King Kong, which I saw last night, has forty-six. But you gotta figure that's gonna grow. [FYI, IMDB has a much shorter list Rev o' Sith, but I guess they aren't as dedicated as the Movie Mistakes folks to that task.] Also, the number sometimes decreases, because the site allows corrections of supposed mistakes. The Corrections page for Sith may be more fun to read than the mistakes page.
Movie Mistakes is a fun site to know about, for now Pirates of the Caribbean has the most mistakes of all time. You've gotta figure that people spending enough time critiquing Gigli. But then that's what Bad Movie Night is for.