Other mistake: After Sonny is shot on the causeway, there are a very large number of bullet exit holes visible on the sides of the tollbooths, which could only have been made if the gunmen shot through the walls (not the windows) of the buildings from the inside. This is common in movies. In real life, bullet entry holes in wood appear as small black dots, not the more dramatic-looking splintered gashes made on the other side of the wood as the bullet exits. (01:52:40)
Other mistake: When the gunman is sitting in the boss' office, the morning after failing to bring Bruce to him, he is shown with a black eye, band aid on his forehead, and the other eye swollen - despite only receiving strikes to the midsection by Bruce the night before.