Movie Mistakes has pointed out many mistakes whether it was factual error, continuity, or revealing. You can view all of them HERE .
-When Bella goes to the Cullens’ house for her birthday party, Alice takes the new camera that Charlie got Bella and takes a picture of Bella and Edward. But when Bella prints out the picture and puts it in her scrapbook, it looks nothing like the picture Alice took. Given we see the entirety of her visit from start to finish, there was no other opportunity for a different photo to be taken.
-When Edward takes Bella to the forest to tell her he is leaving, Bella’s hair hangs down her back. But in a following shot most of it is tucked up in the hood of her coat.
-When Bella pulls up at the Black’s, she spots Jacob, gets out of her truck and her door doesn’t fully close . Later you can see in the background that the door is firmly shut.
-When Edward and Bella turn around to leave the Volturi Chamber, Edward’s robe is tied. When they show them leaving from the back it is undone.
-In the scene where Bella jumps off the cliff, Bella’s eyes are brown before jumping but are blue/green when she surfaces in the water and then back to brown in the underwater and shore scenes.
-At Bella’s birthday party, when Edward pushes Jasper away after attacking Bella, Emmett turns his head to follow Jasper flying through the air. But in the next shot, he is looking in front of him as though he didn’t see anything.
-Right after the scene where Jacob begs Bella not to go to Italy, it shows Alice and Bella driving away in Carlisle’s car; there’s a glimpse of them heading down to the end of the street where a road block fence is visible. That fence is there to stop people from watching while filming.
-During the breakup scene, you see a blue marker between Edwards feet in his wideshots.
twilight 
