Revealing mistake: An enraged Cheetah almost literally mops the White House floor with Diana flailing her around with the lasso. Wonder Woman is sent back first into a pillar, which disintegrates from the impact. Very good, but not so good is the other piece of pillar that comes down and bounces like rubber by her. (01:51:45)
Revealing mistake: Steve's and Diana's Peugeot (2300 lbs) gets sideswiped by a Fahd APC (11.6 tons) but has no damage to its rear quarter panel. (01:20:50 - 01:25:20)
Revealing mistake: Wonder Woman tosses from the shopping mall building the four criminals neatly wrapped up in a banner. The guys smash in their fall the roof of a police car, and they softly bounce as if they landed on a mattress. (00:17:00)
Revealing mistake: Diana saves the kids, with the kids being dummies so obvious to spot it's not even funny. (01:25:40)
Revealing mistake: Steve Trevor approaches and stands before an oval, wall-mounted mirror, incredulously looking at himself and seeing a stranger's face in close-up. Steve finally smiles approvingly, turns to Diana Prince and says, "He's got it! Y'know, I like him!" The camera immediately cuts to two wide shots from behind Steve standing directly in front of the mirror (only a couple of feet away from it), but there is no reflection of Steve in the mirror at all. This error reveals that the "mirror" is actually a hole in the wall (a low-budget practical effect used in films of decades past for such mirror illusions). They probably filmed a lot more footage of Steve mugging in front of the "mirror" but edited it out, because this old-school effect is notoriously difficult to get exactly right. (00:49:50 - 00:50:20)
Suggested correction: They don't use this trick for the scene, the actor playing "the other guy" is standing in front of the mirror himself when you see him in the reflection, since he has black hair and Chris Pine does not. And Chris Pine can only be seen without the mirror. Later in the wide shots the angle of the mirror simply doesn't show Chris Pine's reflection. Only a tiny second at the start of the wide shot can you see it is actually a real mirror, when you see a piece of Chris Pine's hair in it.
As I said, they probably filmed a lot more footage of Steve mugging in front of the "mirror" but edited it out. When Steve approaches the "mirror" in close-up, you can see that there are two distinct actors (which is the whole purpose of the scene): Chris Pine's hair is a distinctly different color and texture, and the actor in the "reflection" is taller. Plus, their subtle body and head movements are not perfectly synchronized, as would be the case in a true mirror-image. It's the old hole-in-the-wall trick.
But it is a real mirror, as it reflects his hair. So it's not a hole in the wall anyway. The back of the head you see when seeing "the other guy" in the mirror is that same guy's head, not Chris Pine's. No need to use that trick.
No, the hair color and texture of the back-of-the-head shot are distinctly different from the guy in the reflection. The whole purpose of the shot is that Chris Pine in the foreground IS NOT the guy in the reflection in the background. The hair color and texture is different, and the guy in the reflection is taller; plus, the body and head movements are not synchronized. Go back and watch the scene (if you can stand watching the movie again).
Revealing mistake: When Cheetah is under fire from the security of the White House and runs towards the camera to grab a column and swing around it like a pole, she is not Kristen Wiig - appears to be a purely CGI shot. (01:50:25)
Revealing mistake: When Barbara is checking out the microfilms that talk about the mysterious stone, you can see in the last one just before the close-up on her eyes that it bears the date "1986", posterior to the movie setting (you may need to pause to read the full paragraph, which says indeed "During 1986, sections were drawn", and it's also worth adding that you can also spot easily that most paragraphs are recycled from one slideshow to the next). (01:13:40)
Revealing mistake: Maxwell is surrounded by the Secret Service, but these trained specialists look around idly and confused when he gets lasso'd and turns towards Diana telling her "Well, aren't you resourceful", as if they wouldn't see the cartoon rope. The guy on the left even appears to be fumbling with his communicator or belt weapon. (01:47:00)
