Other mistake: In the flashback of Bruce Wayne getting killed, his mother is cradling his body and weeping. She has his blood all over her hand from touching his wound. She rakes her fingers across his shoulder and down his chest with her bloody fingers, leaving no trail of blood, but when she places that same bloody hand on her face it leaves blood all over her face and mouth.
Other mistake: Cyborg confronts Batman about throwing Yo-Yo off the roof and then turns on a hologram projector in his arm to show other super heroes. There is a beam emitted from his arm generating the holographic images. We then see him turn the beam off, yet the holograms remain and they have a conversation with them.