Revealing mistake: When the leading hitman jumps from the balcony you see him land on a rubber mat.
Revealing mistake: Healy tears off the October 26 sheet from the calendar, and before the camera cuts away, it shows the October 25 sheet underneath it. That's not how calendars work. (00:11:25)
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: They jump out the office building and the CIA is shooting at the tan Ford Explorer. When the bullets hit the drivers door and other parts they are not making any marks/bullet holes, you can see they are fireworks and not bullets.
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: When doing the blindfold dare, the same clip of them swerving between cars is used 2 or 3 times. (00:44:10)
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: 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 "snow" is obviously fake and it is largely absent on the left third of the screen and, to a lesser extent, the right side. Although it apparently recently started snowing, the snow was not melting when it hit the pavement, which would mean it was cold enough for snow to also "stick" onto metal vehicles (but did not) and the car pulling into the alley should have left tire tracks. At various spots throughout the movie, "snowfall" is spotty and irregular. (00:26:48)