Visible crew/equipment: Crew members are briefly reflected in the front of a train as we see the main characters walk away from the train. Specifically, look for a man in a red tee-shirt.
Other mistake: She's holding a Beretta M1951 9mm single action semi-automatic handgun equipped with a suppressor. She takes a shot, and the hammer is full forward. For the gun to fire the hammer has to be all the way to the rear, and after it's fired, the slide would eject the spent cartridge and grab a new one and the hammer would be to the rear. It's not a cowboy revolver where the hammer has to be cocked every time to fire. (00:54:00)