Continuity mistake: Savant is taking a look at the rest of the team. The blonde Blackguard is goofing off with the guard closest to him as he shimmies. Closer angle, he puts his hand on the gun on his left PC. Next shot, and he's back swaying with both arms down. (00:02:40)
Continuity mistake: At the beginning of the movie, a goldfinch lands in the corner of the prison courtyard. There's a wet/mouldy area in the corner that is suddenly much smaller in the following close-up. (00:01:10)
Continuity mistake: When Peacemaker kills Rick Flag by stabbing him in the heart, the depth of the object changes between the close-up shot of Peacemaker's hand and the next shot, where we can see the part sticking out of Flag's chest has increased. This is before Peacemaker hits the object deeper. (01:31:05)
Continuity mistake: When Amanda Waller orders the blonde subordinate to "Open it", the digital clocks show the same times shown minutes earlier when they had yet to wake up, contact them, talk to them, order them to retreat, witness their change of mind. All of which certainly took longer than a minute. (01:46:45 - 01:49:35)
Continuity mistake: After Waller issued her order to leave Corto Maltese to its fate, Bloodsport turns his back to Starro that is wrecking the city and walks towards the camera. Just a moment before the cut, Margo Robbie is shrugging, a gesture that is supposed to happen in the next shot, and she in fact repeats it in the next shot a second later. (01:48:30)
Continuity mistake: The Corto Maltese Army is storming the pleasure district. As the camera pans from the club doors to the incoming vehicles, to the far left there's a john wearing a brown suit posing one-handed in front of a girl. In the wide shot from behind the trucks, you can see that a soldier pushes the guy back to the wall. But as their commander gets off the hum-vee and yells to search everywhere, the guy is standing in the corner, and at the next cut he's back against the wall. (01:01:45)
Continuity mistake: Look at the overhead shot of the limo approaching the Presidential palace. The gates including the sandbags where military men are stationed are in the shade. We see then a valet open the door for Margot Robbie, and the spot is in the sun. (00:41:35)
Continuity mistake: When Harley bursts out in a Mario Kart-themed insult at the Cortomaltesians, the braid in front of her shoulder is the left one and not the right one. (00:41:00)
Continuity mistake: When Amanda Waller powerpoints Gaius Grieves to the team, from behind she is holding the clicker shoulder-high. Her arm is more outstretched and raised in the wider angle. (00:23:25)
Continuity mistake: Harley slaps the now dead Javelin in the face asking frantically about his incomplete dying words. Literally one moment her hand is on his cheek, the next is mid-length on the shaft of his weapon. (00:26:50)
Continuity mistake: Briefing scene, Ratcatcher 2 raises her hand to ask her question. Notice her right hand, open on top of her thigh. Close-up, and her hand is closed and to the inner side of the thigh. The hand is back in its original position when the first angle is used again. (00:23:45)
Continuity mistake: Peacemaker and Bloodsport are following Amanda Waller through the female section. There are two girls at the table in the center, one with patchwork colorful skin, the other whistling at them. When it cuts to a close-up, neither is in the appropriate position; the whistler's hand dropped and the Kaleidoscope, who already got up, still has her forearms on the table. (00:20:40)
Continuity mistake: In the suicide mission on the beach, Flag makes a run for it behind Harley who just ducked behind a rock. Harley is in a dark corner; Flag dives by her, and the camera angle changes showing her into the spotlight. Sane later when TDK's arms are floating and pass by them in bright light. (00:09:55)
Continuity mistake: Blackguard is panicking because of 'the werewolf' but Rick Flag interjects that he's 'harmless'. He then has to add that he's not -that - harmless, having slaughtered a couple dozens of kids; when the camera angle changes before he says that, the actors have changed positions. For instance, Margot Robbie had her hands clasped together before her chest, then she has them in her lap. (00:05:45)
Answer: It's a combination of various reasons. Will Smith wasn't available to reprise his Deadshot role, so there was a shift in the story. King Shark was intended to be in the first film, but the CGI was too extensive, so they went with Killer Croc. In this film, they took the opportunity to bring in King Shark as the "monster" character. But, this film isn't really a sequel or reboot. Basically, this is a new storyline with new characters, and many of the previous characters are just not in the film, with no exposition on what happened to them, and they may not even be part of this film's "universe." The fact that some of the actors play the same character in both films only serves to muddle the concept of this film not really being a part of the previous film's continuity.
Bishop73