Revealing mistake: When Edward takes his shirt off on the steps in Voltaire, his nipples are different colors and sizes. The closer one is grey while the far is more pink as though the makeup had rubbed off.
Revealing mistake: In the scene of the fight in the chamber of the Volturi when Demitri throws Edward on the stairs you can easily see the body of Pattinson's stunt double, there's a clear six pack, a tanned body and no body hair.
Revealing mistake: When Sam comes into the house and kisses his fiance, you can see the ripples in the edges of the plastic film used to put the tattoo on his arm.
Revealing mistake: When Bella and Edward return from Italy, Edward 'disappears' when Charlie enters the room. You can see behind the door when he is in the room that there is nowhere/not enough space for Edward to hide, but when Charlie leaves the room, as the door shuts, Edward steps out from behind it.