Revealing mistake: Davey at the beginning of the movie is looking at the newspaper he's delivering to Mr. Wayne Mackey. Just from a glance at the page you can tell that something is off, since the article supposedly about a missing boy appears to be written entirely in first person. Upon closer inspection, turns out that it's filler text from chapter IV of Robert Louis Stevenson' s "Treasure Island". (00:01:30)
Revealing mistake: When Orm presents the weapons to Manta as a water hologram, Manta walks right through the hologram with half of his body. This arm passes through the hologram made of water and even makes a splash sound. However, there is not a single drop of water on Manta's completely dry clothing after this.
Revealing mistake: When the agent is questioning Fat Freddy after the cop finds him with coke and a gun, she puts a phone up to his face and says "say cheese." She holds the phone up to his face with the screen facing him. You hear the click and beep of the phone taking a picture, but when she turns the phone around, it's still on the locked screen with just the background and a clock. (01:06:45)
Revealing mistake: Parzival heads back to the Halliday Journals to watch the scene of Halliday and Morrow parting ways again. There is glass between him and the scene and some camera angles show Parzival through the glass from inside with the scene reflected on the glass. However the reflection is wrong. Morrow is standing on the right with Halliday on the left, but when showing their reflection in the glass, their positions are not reversed. (00:23:45)
Revealing mistake: When Kurt and Elisabeth are looking at the painting of the Third Reich caricatures, in the shot focusing on them, a little girl in the background can be seen glancing at the camera. (00:01:45)
Revealing mistake: Callahan proudly shows to a policeman an issue of the Portland State University "Vanguard", the magazine that is publishing his comic. Looking at the prop, it is instantly suspicious because Callahan's name is all over it like he's a celebrity, and in fact, the article on it is nothing but a copy and paste of Timothy Egan's "Defiantly incorrect" article from The New Yorker celebrating John Callahan's talents in 1992. (01:12:55)
Revealing mistake: The anchor rope around Maddy's neck is loose enough for her to remove.
Revealing mistake: The bottom third of the left-hand side of the screen is a "filler." At the top part of the left-hand side, there's a bicycle hanging on the wall, a square wall shelf, and a 3-Light Tree Floor Lamp. About two-thirds of the way down the wall, there's an inverted image of the items at the top - the angled edge of the wall (which does not line up with the rest of the wall because it's inverted), half of a bicycle wheel, the square wall shelf, and 3-lights of the floor lamp at the bottom of the pole. (00:01:54)
Revealing mistake: When Scott dislocates his thumb to get out of his hand cuffs, they are fully tight. But while he slips his hand out you can see the cuff is all the way loose to allow Van Damme to get his hand out.
Revealing mistake: Annie hears the sound of scribbling in the distance and follows the sound into Charlie's room. When she enters at 1:26:13, you see Charlie's doodle book on the bed being written in and the pages flipping on their own. If you look to the left of the bed, there are a few visible wires running from the book towards the wall to turn the pages. In the photos, they can be seen towards the bottom of the nightstand. In motion, it's pretty easy to see the wires bouncing around (from 1:26:13 to 1:26:21). (01:26:13)
Revealing mistake: After Robin starts to believe that the Teen Titans are in fact a joke, he gets sad and goes out a hole in the wall saying goodbye to them. He fires his grappling gun up and steps out of the wall. But his arm remains bent as he stands casually in the air to be taken upwards. There is no effect of gravity or any realistic body motion in those moment. As his weight should have had him dangle down with his arm stretched out above him and him swaying like a pendulum. Instead he appears as a stationary action figure in a single pose with his elbow bent as he's taken up.
Revealing mistake: As the girls handle the drone, and even more obviously when it drops on the security guard's head, it is clear by the way it bounce and clatters that it is almost weightless and certainly couldn't knock someone out cold. (00:59:50)
Revealing mistake: When Asher is shooting a bolt-action sniper rifle there's no casing ejecting from the rifle as he reloads it with the bolt. (00:48:30 - 00:49:25)
Revealing mistake: While they're finally on the rapids, the girl blindfold keeps changing position from her neck to her forehead. (01:40:59)
Revealing mistake: The paper towel holder is in front of Mr. Truett when he joins his son at the diner table. After Zach leaves, Mr. Truett moves the tray off the table and (off-screen) probably moves the paper towel holder to his left where Zach was sitting. However, some shots show the paper towel holder too close to Dave (which would be near the middle of the table) while other shots show it at the edge of the table (in front of Zach's empty chair). (00:20:35 - 00:21:40)
Revealing mistake: Near the end when the orphans are exiting the building in the bus, you can tell they practised the sliding part. There are marks in the roof of the bus from previous takes.
Revealing mistake: Vera types "Nico Lasarte - Murdered - 1989" into a web browser. When she clicks the search button and the screen changes to list the search results, Vera's position in the frame can be seen shifting on-screen, revealing that the shot of the search bar and the shot of the search results were two separate shots merged together. (00:57:20)
Revealing mistake: After Jess leaned her bicycle against the pole, it slid down onto the ground. In subsequent views of the bicycle to Jess' side, the bicycle appeared to be upright and not what would be expected if it was lying on the ground. The height of the bicycle's seat should have been closer to the chair's arm, not Jess' shoulder. At a different angle before Jess got up, the bicycle was positioned like it was right after it slid onto the ground. (01:04:02 - 01:05:47)
Revealing mistake: When Scott is fighting Ghost, as Pym is planning to dive, Ghost throws Scott through a wall and you can see the braking cable around his/the stuntman's waist and across the floor. (01:16:48)
Revealing mistake: Normally I wouldn't consider a bad CGI effect to be a mistake, but when Elise finds the hidden keyhole in the wall in the basement, the effect is comical if you pay attention. The way it appears as she scratches is pretty unnatural, and the pieces of paint that fall practically look like cartoon pieces if you pay attention. The shadow of her left hand also looks a little too sharp compared to the rest of her (somewhat softer) shadow, revealing it was likely rotoscopped in some way.