Revealing mistake: In the Batcave, the protagonist looks at the newspaper clipping about the death of her mother. The rightmost column has a headline "Children traumatized after ride of terror", and a sign ("by Lucy Moguire"). And yet, it begins like this; "With the population of the planet ever increasing, so does the demand on Earth's resources." It's a lazy copy and paste by the prop department, putting some global warming report as filler text. (00:27:40)
Revealing mistake: Batwoman gets shot in the alley; the bullets create bad looking CGI sparks each time they hit her suit. When she gets back to the cave and sits down as Luke scolds her, you can see her suit bends and folds at the breastplate all rubber-like, making even more unlikely the fact that bullets would create sparks on impact (for what is worth, in the following episode there's a close-up of a bullet hitting the breastplate of the suit and there is no trace of sparks and not the slightest give from the material). (00:02:00 - 00:03:55)
Revealing mistake: The Wonderland gang henchmen dispose of the Crows' van through fire that causes a nice, clean, completely fake CGI explosion, looking entirely disjointed from the rest of the background. (00:02:00)
Revealing mistake: During the sequence with a crowd in front of the Gazette looking at the dummy on the stairs, there is a shot with the camera panning up (right after Kate arrives). Look in the crowd on the left side; a kid is following the movement of the camera on the crane instead of looking at the 'crime scene'. (00:11:50)