Revealing mistake: When Leo is laying his dead kids on the grass, the little girl keeps moving her eyes and breathing.
Revealing mistake: The overhead shot of Aron swimming at the end of the film shows him having two full arms.
Revealing mistake: After the prince is crowned king, Robin and his mates leave the castle. If you look to the upper-right of the screen, atop a hill in the distance, you can see a modern-day metal telegraph tower (cinematic version).
Revealing mistake: In the beginning scene when the dragons are attacking Berk, it shows several sky torch things being raised into the air. As one closest to the camera is rising, a Viking throws a burning stick at it to ignite it. If you watch it closely, you can see the torch starts burning first to the far left, well out of reach of the thrown fire. Even allowing for fumes igniting, the fumes nearest the flame should light first.
Revealing mistake: During the shower scene with Ally, part of Tyler's scratches disappear, due to it being makeup that was washed off in the water.
Revealing mistake: Despite receiving several shots and crashing against other boats, Elise's wooden boat structure remains undamaged.
Revealing mistake: When Dominic West is captured and chained in the Pict village, you can see a hearing device in his ear. (00:38:55 - 00:41:35)
Revealing mistake: Throughout the movie, people getting shot almost always don't have the shot angles line up with how they appear. This is especially obvious in the end scene with Hit Girl shooting the gangsters: she might shoot someone at an angle from the side, but the shot appears to have come from directly behind the person.
Revealing mistake: In the final scene we see a bomb disposal technician disarming a nuclear bomb. The screen of the laptop is shown in one brief shot. It displays a database program of some sort, and has been filled in, perhaps to look like it contains lots of helpful, bomb disarming related information. However, it is actually just random button mashing; most of the 'codes' consist of the letters 'dfgty'. Look at where they are on the keyboard. Very lazy: dgght dfhdftyh fghrthy.
Revealing mistake: In the scene where Rachel McAdams goes to Patrick Wilson's office to explain why she left the bar so abruptly the night before, there are four TV monitors behind her as she does those weird charade movements. Only one monitor has a picture. The picture is of the New Jersey anchors of the job from which she was previously fired. Also, the characters in the picture never move.
Revealing mistake: Throughout the phonecall between Killer and Lucy, the call duration on the iPhone stays the same at 00:03. (00:37:00)
Revealing mistake: Horvath is trapped in the bathroom mirror, and after knocking on the mirror from the inside, a boy comes over. You can see that the shadow from the boy's shoulder is falling on Horvath, and when he turns and falls over, if you watch closely, you can see that the boy bumps into Horvath's arm. This is because the boy actor is standing in front of Horvath's actor to achieve the mirror effect.
Revealing mistake: At the end scene when the Sheriff is escaping in the truck away from the nuclear blast, the truck begins to flip through the air. While it is flipping we see under the vehicle and can see the hole they use to launch a post to help flip the vehicle for the stunt. A brief puff of white smoke also emanates from that hole briefly during the flip.
Revealing mistake: When Mark gets a nasty note from a Harvard classmate and storms out of a computer class, a directory sign saying "USC College of Letters, Arts & Sciences" (ie. University of Southern California, not Harvard) can easily be seen on the hallway wall through the door as he opens it and walks out.
Revealing mistake: Reverse footage: when the sheriff first comes to talk to Ree, the neighbor is shown eavesdropping, walking out past a truck. The logo and the license plate on the truck are reversed, as if in a mirror.
Revealing mistake: When Jensen is investigating the missing 4 million dollars from the account, we see the screen on his laptop. Among other things, it shows a picture of Fadhil's passport, which looks like it has a watermark on it, readable as http://slawek.com. Indeed, going to http://www.worldpassports.org/americas/pages/bolivia.htm you will find the passport pictured there. (01:01:35)
Revealing mistake: At the end of the film when the two Detectives are checking the sewer for the missing button. As the male Detective is lifting the sewer, the inner sewer lid paint peels back, exposing a white color of the sewer lid. Which makes you realize the sewer is likely made of a light wood or plastic (making it easier for actors to lift lid). It is obvious the "Props Crew" didn't do a good job in painting the sewer. It is made more obvious when the female Detective tries to hide the peeling paint by very quickly sliding her hand over the exact spot its peeling. Then in the next shot the male Detective does the same, but in the corner.
Revealing mistake: After exercising, Valerie is in bed watching the news, then the scene changes to a shot of her house showing a Honda Accord at the 2002 meeting but this model did not get released until 2008.
Revealing mistake: At the book fair, Marcus briefly pauses to listen to Derek Jacobi's book reading. When he walks away, the camera follows an extra to her seat. If you watch when she enters the scene from behind the sign, the extra hesitates until the actor playing Marcus walks away, which is apparently her cue. (01:43:45)
Revealing mistake: When Mel Gibson is fighting the boyfriend, he flips the table at him, and you can see that it's a double. There are other instances where you can spot the double, but this one is so close and clear. (00:26:55)