(at around 1h 13 mins) In one scene an uninjured Dolores looks out of Nya's intact apartment window. In the next scene the window is shattered and Dolores' arm appears to have been grazed by a bullet. This jump is explained by the deleted scene included in the Blu-ray release: Skeletor was hiding in Nya's apartment (hence the "fresh" blood Dolores notices on the floor), inside the closet. When he jumps out and tries to kill Nya, there's a confrontation between him and Isaiah, which leads to Skeletor flying through the window.
(at around 26 mins) Dolores states that the elevator is broken, but Isaiah is seen using the elevator to leave the building.
(at around 29 mins) When the Thief is breaking into the ATM, Skeletor comes up behind him, and scares him, causing him to turn around to face Skeletor before he stabs him in the chest. When the Purge Organizers are reviewing the footage of "The First Purge of the evening," the footage shows Skeletor stabbing the thief from the side, before he has the chance to turn around.
(at around 1h 19 mins) In the staircase scene where Dmitri is fighting with two mercenaries, one is shot and blood splatters on the wall. In the camera shots that follow, the blood is no longer there.
(at around 33 mins) When Isaiah is running from sisters' explosive devices a baby toy on the ground suddenly just disappears.
(at around 50 mins) When Chief of Staff - Arlo Sabian is looking at the latest statistics, there is a graphic of a pie-chart on the screen behind him. It has segments labeled 5%, 25%, 16%, 14% and 50%. This adds up to 110%.
At the end, Dmitri creates an explosion by shooting a block of C4. C4 is highly stable to the point that it can only be detonated by a shock-wave producing percussion cap. Shooting it, or even setting it on fire, will not cause it to explode.
End of the film, C4 goes off in huge slomo ball of flame the heroes avoid. C4 has no rolling flame, its an expansion shock wave at the speed of sound there's no avoiding. Somewhat less cinematic though.
This movie takes place before any of the previous Purge films. However, a Halloween (2018) poster can be seen in one of the characters's bedrooms. The poster shouldn't have even been made yet considering the movie wasn't even a thought during the time this film takes place.
Staten Island covers roughly 60 square miles. Most of the African Americans and Latinos live in a narrow strip near the Staten Island Ferry Terminal. The film, however, shows them running around all areas of the island, including some areas which are MILES away from their homes.
The main characters are "hiding" from the Purgers....inside of an apartment with the lights on and the curtains wide open. Worse, they are standing in the windows looking out.