Revealing mistake: When the leading hitman jumps from the balcony you see him land on a rubber mat.
Revealing mistake: When they are in the hospital van, taking the senator to triage, and they receive fire from the helicopter, one announces that "Randall is dead" referring to the young man in the back of the van. It then cuts to his corpse - however, a split second before the scene changes away from his face, his eyes move towards the camera. (00:56:35)
Revealing mistake: When a contractor fires a grenade at an enemy technical, the truck visibly explodes and moves upwards before the (most likely) CGI projectile hits it. (01:02:00)
Revealing mistake: During the face-off between Bucky, Captain America and Iron Man at the end of the film the fake snow is seen stuck to the actors after they fall down. It remains throughout the scene rather than melting as real snow would.
Revealing mistake: When Jerico is having his surgery the angle of the device that will be transmitting the memories is inconsistently angled in the real shot versus the monitor image.
Revealing mistake: After Jyn has retrieved the data file containing the Death Star plans, Krennic is shown walking in a hallway with two other Death Troopers and pushes a button to open a door. The door begins to open before Krennic actually pushes the button to open it. While his hand is not seen touching the button, the sound of the button being pressed is still heard. (01:51:10)
Revealing mistake: When Dylan is looking at the news articles in Thaddeus' cell, the camera pans over to one of the articles with the headline, "I am a victim": Thaddeus Bradley. The opening paragraphs on the first column are repeated throughout the entire article.
Revealing mistake: When Apocalypse first introduces himself to Magneto in the factory and tries to persuade him to join his side, a seam in Apocalypse's facial prosthetics next to his mouth is starting to come apart during a close-up shot.
Revealing mistake: In the opening scenes, we see a very pregnant Draka reclining on a bed of animal hides as Durotan watches over her. In the extreme closeup, we see Draka twitch her lips, and her small tusks flex from side-to-side with her lips, instead of remaining firmly aligned with her jaw as they should.
Revealing mistake: During the live stream, the second punch that the president receives misses him. However, he reacts to the punch. (01:15:50)
Revealing mistake: The subway station is identified by its internal signs as "Central" station, but as the Suicide Squad enters its exterior entrance, the sign above declares that it is "Bay St." station. Bay Street Station in Toronto is frequently used for movie shoots, as it has a complete lower platform which has been out of service for decades (https://en.wikipedia.org/wiki/Bay_ (TTC) #Lower_Bay).
Revealing mistake: In the Gatling Gun scene when the camera cuts to a short couple frame shot showing a closeup on the .45-70 Government ammunition casings on the ground that are falling from the gun, the casings are star crimped. Star crimped casings indicate blank ammunition. Standard ammunition isn't possible with star crimping. The size and casing shape indicates .45-70 Gov which was popular in these guns at this time. (01:46:40)
Revealing mistake: When James jumps off the SUV about to crash through the parapet, Ice Cube rolling on the floor looks 20 pounds lighter - that, or it's just the stunt double. (00:09:30)
Revealing mistake: Despite Sigourney Weaver supposedly having had her fingers cut off if you watch her when she's in her straitjacket you can see her fingers moving around.
Revealing mistake: Just after Sang-hwa and the baseball team seal the doors, it cuts to a man in a checkered shirt clinging onto a set of chairs, getting attacked by a zombie. In the closer shot of the zombie biting onto the man's neck, for a brief moment, a blood pack can be seen just above the black T-shirt he is wearing under the checkered shirt. (00:45:43)
Revealing mistake: Set in Pittsburgh, PA, scenes were obviously filmed out of sequence. Many scenes were "out of sync" with the snowfall, whether in progress or amount (if any) already accumulated. For example, there was no snow downtown, but views from the helicopter showed snow-cover around the nearby parkway (Route 376). In another scene, it was snowing when Ryan turned his Jeep into a downtown road that was covered with at least one inch of snow; switching to a "live" newscast, the sun was shining outside.
Revealing mistake: When Gabby and Fin are hanging off the building in Las Vegas, you can see that Gabby isn't holding on to anything in some close-up shots. (00:11:47)