Continuity mistake: When Sammy first offers the drink to Diana (in a close up), Diana takes the mug in her left hand. Just before the camera switches to a long shot, Diana switches the mug to her right hand. In the long shot, Diana still has the mug in her left hand and she sets it on the wall to her left. The camera switches back to a close up and Diana again has the mug in her right hand. When Steve asks her to dance, Diana again sets the mug down on the wall, this time to her right.
Continuity mistake: At the end after the massive explosion on the runway, two German soldiers get up unscathed and remove their gas masks. They suddenly appeared, as no one else was there, only Diana, and they are only a few feet away from the crater.
Continuity mistake: At the end when Diana is moving through the crowd approaching the memorial wall, the Scottish sniper is behind her. In the next shot when she turns around, he is again behind her.
Plot hole: How is it possible that Diana is unaware of the concept of marriage? She has a grasp of multiple languages and cultures and can recite Socrates. Socrates often spoke of marriage, so even if her people do not marry, it makes no sense that she is completely unfamiliar with this human custom.
Character mistake: Chief says the poison gas should be flammable because it's hydrogen-based. Hydrogen is the most common element in the universe, and there are plenty of non-flammable substances that contain hydrogen - the most notable of which being water.
Continuity mistake: Wonder Woman is fighting the soldiers on the second floor in the village, after she retrieves her shield. Her sword goes from properly in her hand, to being held by the blade, to held by the blade upside down, but when she looks up, just before going through the window, the blade is normal again. (01:18:05)
Continuity mistake: When the picture of Diana and Steve and co. is taken in Veld, she is wearing her black cloak, but she left that and her other clothes in the trenches, on the other side of no man's land.
Continuity mistake: When Diana and Steve are held at gunpoint in the alley, the gun's hammer is drawn back and in the next shot it is in the resting position. (00:53:15)