"Moviemistakes.com users have begun critiquing some of the goofs that exist in the film, and it seems that there are quite a few noticeable blunders in Eclipse . . . though none will quite live up to Gil Birmingham (who portrayed the wheelchair-bound "Billy Black") driving the truck or the very visible make-up lines in Twilight.
Including those noticed by the site as well as my own observations, here are some of the most interesting slip-ups caught in Eclipse so far (which, if nothing else, will give you something to look for the next time you see it again).
"Aro"/"Arrow": Remember the "Volturi Featurette"? If not, here it is. Upon watching it, you'll notice that "Felix" (portrayed in The Twilight Saga: Eclipse by Daniel Cudmore) says "Aro" with the pronunciation "Ah-ro" in this video. In the film, however, it's pronounced as "arrow." When I asked Daniel Cudmore about this mix-up at the Eclipse premiere (see here for the video), he chalked it up to "difference of opinions in directors . . . each director wants it a different way."
"Jasper Hale" at lunch, graduation: First of all, "Jasper" was no longer in school in the events of Eclipse (the book). He, "Rosalie," and "Emmett" had all graduated by this point. The fact that he was a part of lunchroom events in the film has been received by some commentators to one post as a continuity effort: since he was on the biology field trip with the group in Twilight, he'd been grouped with those characters in age and bringing him back with the same group in New Moon and Eclipse made sense in that regard. Also, there are probably a good list of reasons why "Jasper Hale" (Jackson Rathbone) and "Alice Cullen" (Ashley Greene) were seated next to each other at the Forks High School graduation ceremony in Eclipse (i.e., this offers a flash at their romantic bond, makes the number of shots needed in this scene lesser) but this is a mistake as well since their last names are quite spread apart, alphabetically.
"Edward's" earlobe, skin: In most of the meadow sequences, there is a lot of lip-locking between "Bella" (Kristen Stewart) and "Edward" (Robert Pattinson). This is no blunder, to be sure, but there are at least two flaws which can be found in these moments, and they involve an earlobe and some sparkle-less skin. In one moment, "Bella" reaches over and places her hand on "Edward's" face. In doing so, she brushes by his earlobe and it moves (folds in a little bit). In the Twilight series' mythology, the vampires' hair is about the only involuntarily mobile thing, but vampires like "Edward" can choose to move around. In other words, the only way that any part of their body can be moved - particularly by a human character - is if they move it themselves. An earlobe, at least not usually, isn't the type of appendage that people (or, presumably, vampires) cannot move from internal force, so the fact that she brushed it and it folded in means there was a slight oversight (or that the kiss was too steamy to edit it out!). Also, as pointed out by users on MovieMistakes, there is a point in the final meadow sequence when the sun is clearly out but "Edward" is not sparkling.
"Hungryward": In the first scene featuring "Jacob Black" (Taylor Lautner), "Bella" and "Edward" drive into the school's parking lot, and he speaks to her about not getting out of the car. At this time, his eyes are golden. Later in the day, after "Bella" takes off to go on a ride with "Jacob" to La Push, he comes to her house and has furiously black eyes. Some, in discussions, have argued that this was a bit of homage to his sudden, furious worry over her leaving, but when it is discovered that an intruder ("Riley," Xavier Samuel) has been in the home, they return to the "Cullen" house to discuss it with his family . . . and all of their eyes are just as black, revealed to be a result of their hunger. This sudden transition would mean that "Edward" had not been starving until that day, which is unlikely given the status of his family and the way that Twilight lore indicates hunger's effect on the color of their eyes to be gradual.
Cuts, bitemarks, and dismembered heads: There are a couple of continuity errors associated with the location or placement of things in the film, of course, but these are a little more interesting than most. First of all, the bite that "James" inflicted on "Bella" hasn't been in the same place throughout the entire Saga, so it's probably no surprise that in Eclipse, the bite isn't where it was made in the first film. Additionally, the cut that she inflicts upon herself at the end of the film was on her middle arm, but "Edward" reportedly goes to bandage it up near the wrist. Finally, one MovieMistakes contributor points out that "Victoria's" head, when lying on the ground, has its eyes open at one point and closed in another shot.
Purple fire: No "purple-black smoke" was used in the film, though the book states that this is what is produced upon burning the newborn vampires from the army. The same was true in Twilight with the destruction of "James.""
So comment below on the ones that you caught...