Deliberate mistake: Considering the position of the surveillance camera (height and angle - almost parallel to the side of the building as well as to the sidewalk), plus the lens being indented within the outer frame, it would not have been able to capture a view of Redd on the sidewalk below like it did. (00:24:40)
Deliberate mistake: The thug wearing headphones and facing the money on the shelves did not notice that Savage forcefully opened the door several feet to his right, slamming it against the adjacent wall, or that Savage had entered the room. The bang to and vibration from the door hitting the wall should have been enough to overpower the sound from his earphones, but - even if they weren't - his peripheral vision should have sensed the door opening and Savage entering. (00:02:55)
Deliberate mistake: At the end of the car chase with Penguin Batman's car drives upon a ramp at high speed before the explosions occur but his car only appears flying through the air and landing 15 seconds after the explosions. That's quite a long jump. (01:23:33)
Deliberate mistake: One of the first shots in Greece shows Benoit Blanc and Lionel standing on the pier. As director Rian Johnson himself says in an interview for the Vanity Fair Youtube channel, "Matches nothing else in the scene lighting-wise, but it's gorgeous soooo...who cares." (00:13:30)