Revealing mistake: Before confronting Stephen, Django shoots Candie's sister. He is up high on the stairs with her on the first floor. He is far to her right. But when he shoots her, she flies straight backwards into the other room, and you can see where her dress was pulled by a rip line.
Revealing mistake: Near the end after Django shoots "Moonlight" and two other guys, Moonlight is on the floor in pain. When he squirms around he puts his right arm out, revealing a wire from under his shirt going up his right arm. Most likely this was used to ignite the squib charge on his right shoulder. (The first shot Django made in this scene was shooting Moonlight in his right shoulder). (02:36:50)