Revealing mistake: The final scene is filmed in Brant Rock MA, and the weather is blatantly CGI. If you notice almost everyone is bone dry in a supposed driving rain storm. Look especially at the character perched on top of the submarine tower. For contrast note the "pizza delivery" scene where it is raining heavily and everyone involved is soaking wet.
Revealing mistake: During the police chase with Gabriel on his motorcycle, he stops and turns to start shooting at one of the cops. By appearances, Gabriel is using a standard Glock which had a magazine capacity of 15 rounds. He has no extensions on it at all with the handle and magazine visible. Yet he proceeds to fire the gun 33-35 times at the cop car without reloading and in continuous fire. (00:57:55)
Revealing mistake: Fight in the toilet of the Paris nightclub: the presumed Lark rips out the sink's drain and begins assaulting Tom Cruise with it; Walker intervenes holding him, but the nimble Asian does a flip and brutally tosses him to the ground. As Henry Cavill is bent over before being snapped to the floor, on his back, you can definitely see a protective pad through the jacket. (00:31:52)
Revealing mistake: When Evelyn is hanging the clothes after washing them, they are already dry.
Revealing mistake: When Claire hangs up the phone at the start, the phone is actually off. (00:10:30)
Revealing mistake: Baca is using a pistol to shoot the zombies towards the end and still has this same pistol at the end. When he's on the ground about to shoot himself to stop from turning, it shows a close up of his pistol which reveals it's a 6mm BB gun. (01:20:15)
Revealing mistake: Jack and his brother are driving in a truck and the speedometer shows zero.
Revealing mistake: Just after Proxima Midnight and Corvus Glaive land in the train station, there is a wide shot where they begin approaching Wanda and Vision. In the wide shot, their shadows do not appear to match up with each other, despite being under the same lighting. Proxima Midnight's shadow is positioned in front of her and is quite heavy, but Corvus Glaive's shadow is positioned more to his left and is much lighter than Proxima's. (00:40:20)
Revealing mistake: During the big shootout on the freeway at the end of the movie, there is a camera pan over all the cars stopped in traffic. There are no people in any of the cars. The shot is so high that you would still be able to see people crouched down if that was the case. (01:56:47)
Revealing mistake: When Chewy puts his hand on Han's shoulder at the end, Joonas Suotamo's finger is visible through the fur.
Revealing mistake: When Drake's henchmen are chasing Eddie on the street while he is riding his bike on the sidewalk you can see the stunt man driving for him.
Revealing mistake: As Will and Ben are wrestling for the gun, it goes off, shooting Ben in the chest. When you hear the shot you can see the gun is lying on Ben's chest with him holding it, and it's pointed pretty much at an exact 90° to his side. It would have barely grazed him at best and would have left a long scratch/cut at that angle. Yet as they get up the shot is perfectly centered on his chest and round as if it was a direct shot. (00:24:55)
Revealing mistake: Cottontail gives Tom a wet Willie. However Tom reacts before Cottontail touches him.
Revealing mistake: Right before the scene where Freddie meets with the band to try and make amends, he's arguing with that one man in the rain. After he walks away and it's raining only on him and on the pavement. If you look to the right there is no rain coming down on the grass or trees or anything else.
Revealing mistake: After young Donna and Bill are swimming back to the boat after what is meant to be a beautiful ocean swim, Donna climbs up into the boat. In the high shot we can see a line or seam in the floor under the water that gives away it's being shot in a pool.
Revealing mistake: The paddle steamer on which Wilde crosses the Channel has her name "Waverley" visible on the bow. The Waverley, the world's last seagoing paddle steamer, was launched in 1946, 46 years after Wilde's death. Replacing the name with the name of a real paddle steamer of the era would probably have been a good idea.
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: 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)