Revealing mistake: When Helga is sent flying into her room, the support cable that is attached to her is visible.
Revealing mistake: When Pinback is hanging from the lift, just before he decides to undo the bolts, you can see a piece of wood supporting his back. (00:43:00)
Revealing mistake: In the very early scene in which Zed points his revolver directly toward the viewing audience and shoots, it's visible that there is no ammunition in the gun's chambers.