Revealing mistake: When making traps, he's harvesting powder from a spent shell (primer has been struck). (01:05:50)
Revealing mistake: When Finney is looking for the bike lock's combination written on the wall, the distance between the mattress and that wall (several feet) can be seen. However, the next time Finney wakes up on the mattress, the mattress is against or almost touching the corner, but the mattress was not that close to the adjacent wall. Furthermore, when the Black Phone rings, the mattress is the same distance from the phone as it originally was (which would be several feet away from the wall). (01:04:59 - 01:10:53)
Revealing mistake: The jaguar near the start jumps onto the bar and prowls along it. It knocks over one glass with some force, which shatters, but the second glass is barely tapped by its foot and it smashes to bits too, when it should just have been pushed out of the way.
Revealing mistake: Deacon uses "hidden" food to get the dog to come up to him. The "treat" is largely concealed - but the dog's slobber gives it away. The camera shifts after Deacon's hand goes next to the dog's mouth, giving the impression that Deacon is just petting the dog under his neck. (00:06:35)
Suggested correction: He was feeding him. You can see him eating out of his hand. The food isn't "hidden" You can hear the dog sounding as if he were eating something and his face is in his hand. Those were added sound effects in post. At first glance I got the impression he was giving the dog a treat as they were pals.
Part 1: Based on the circumstances plus Deacon's actions immediately before, during, and after his encounter with the dog, I believe it was a lousy attempt at luring the dog but trying to give the impression there was no lure (food). Deacon did not have food when he came out of his house and wasn't expecting the dog to be there. Deacon even pointed his right fingers toward the dog when he said, " You [are] the one [who has] been gone for the last two weeks." Deacon stoops down and [continued].
Part 2:...makes an effort to point his right hand fingers downward, again giving the impression he wasn't holding anything (food). If feeding a hungry, cautious dog, I think he would have displayed the food in the palm of his hand (what is there to hide if actually feeding the dog?). When "sneaking" the food into the dog's mouth, a small piece can be seen falling to the ground. Deacon holds the dog under his neck, probably to keep the dog from reaching the food that has fallen.
Part 3: (The dog later picks up the piece that fell.) Taking all these odd movements into consideration, I'm sticking with my assertion - Deacon "surreptiously" lured the dog, but his actions were noticeable, thereby revealing what was actually happening. Also, if the dog was missing for two weeks, Deacon would not have been likely to bring food out for the dog that morning. Anyone wanting to view the scene and serve as a tie-breaker, start at 00:06:26, watch Deacon's right fingers @ 0:06:32+.
Revealing mistake: When the military security checks Flash's phony badge, the name on the personnel list to the right does not match the fake identity; Barry's false identity is "Rowe, Wesley", but in the list the name "Band, Ryan" is highlighted. This mistake was not present in the theatrical 'Whedon' cut where the name was altered to match. (02:27:05)
Revealing mistake: When Bloodsport rescues Ratcatcher 2 from on top of the car, they don't actually dodge the arm coming for them but are going straight through like it's not even there. (01:54:16)
Revealing mistake: When the McDonald's bag could be seen setting on the desk, it was about as high as Slahi's chest. When there was an angled view of Slahi from the chest up, the McDonald's bag was as high as his neck (and, obviously, not setting directly on the table). (00:20:20 - 00:21:23)
Revealing mistake: Much of the cemetery scene with the Mentor was "green screened." The backgrounds were inconsistent (e.g, trees and tree trunks) and sometimes the Virtuoso's and Mentor's head were practically together when facing each other. The sizes of their heads also varied at times. The Mentor also was at an angle to the Virtuoso during his long speech, at least giving the impression that he was using cue cards to remember his lines. A couple times, the Mentor looked like he lost his place. (00:15:24)
Revealing mistake: Right after baby Estella is born there is no umbilical cord.
Revealing mistake: The "movie set" steps were so steep they almost looked like they were flat against the wall and the handrail posts were so close together they looked more like vertical blinds. The little dog was able to scale the steps one-by-one, but the larger dog had to leap with effort to get to the top. Also, the baseboards on perpendicular walls (lower right-hand corner of the screen) were not in alignment (off by at least 1"). (01:11:54)
Revealing mistake: The possessed "Helen" that Fr Daniel threw to the ground by grabbing the back of her hair landed like a stuffed doll, not person. The "body" was mostly padding and the fake "Helen" kind of bounced or teetered after hitting the ground. Also, her arms stayed hidden in front of her whereas a real person would be stretching out or moving arms to try to land as safely as possible. (00:21:35)
Revealing mistake: The "bridge" within the crime scene tape is obviously a prop. It should be a continuation of the road, but it is tilted to the left and is more vertical (around 45°). The bridge isn't even very high. When Byron and others go under the bridge to look at the dead girl, there is only a few feet above their heads (clearance under the bridge). (00:04:54)
Revealing mistake: Maurizio tosses on the table the newspaper with the article about the new "P.G." brand launched by his cousin Paolo. The article itself is a copy/paste of the same paragraphs repeating a bit of history of the Gucci family and brand. (01:11:05)
Revealing mistake: When Jake is sliding on the floor at the mall trying to grab his retainer, streak marks are visible on the floor from where they practised the shot.
Revealing mistake: DEA Agent Rick Bowden was already seated "in the best position" before knowing where Ross would sit in the SF library. Chris Tarbell already had a surveillance camera behind the seat Ross chose, giving him a clear view of Ross, also before knowing where Ross was going to sit. Even if there were cameras in other positions, the DEA Agent and Chris Tarbell being at the right spots in advance was too coincidental to be by chance alone. (00:02:09 - 00:02:30)
Revealing mistake: When Knox pulls up behind the parked BMW, the BMW's red tail light reflectors are not real (and maybe the car isn't, either). The reflector on the right side, in particular, is not fully connected to the car. (00:03:55)
Revealing mistake: At Wendy's 50th birthday party, the helium balloons did not move, even when her daughter Liz walked next to some of them while carrying a birthday cake with lit candles. (00:01:44)
Revealing mistake: The picture on the wall of a younger Mike on a horse shows his groin against the horse's neck right below its ears - obviously photo-edited/photoshopped. (00:04:29)
Revealing mistake: In a random act of road rage, Carnage sticks out a couple of tentacles, effortlessly lifts up a truck that was driving by, and tosses it off the bridge. Great, but no matter how strong Carnage and each tentacle of his is, it can't nullify physics; it lifts that vehicle stopping entirely its momentum, and Carnage's car does not even remotely budge for the added weight. (00:45:25)
Revealing mistake: When "Snowball" is sleeping on Lena's bed, it is obviously a "stuffed double" (stand-in). Snowball is usually partially hidden behind the dog (so breathing doesn't need to be shown/mimicked). The failure of Snowball to make even a slight movement is a giveaway (e.g, no ear movement when Lena starts talking), but even the stuffed lion, in itself, is not a very good replica - it simply looks fake. (00:33:44 - 00:48:20)