X-Men: First Class. Something to be proud of team!
According to MovieMistakes.com, the X-Men prequel flick has a documented 24 errors strewn throughout the film. Examples of such blunders include an actress's hairstyle changing mid-scene (bad January Jones!), a wrongly-dated Nazi coin and a character's hand changing position after being stabbed and pinned to a table with a knife.
We know someone's continuity person who's not getting hired back for the sequel! Whomp, whomp!
FYI - Pirates of the Caribbean: On Stranger Tides came in second, with 13 errors, some movie called Paul took third place with 12 mistakes, and Super 8 and The Green Hornet share fifth spot with 10 errors each.
Steven Spielberg! Really?! We're shocked