Revealing mistake: Just after the B.R.O.T.H.E.R.H.O.O.D. discover who UB is, it cuts to UB in his apartment, apparently having a kung-fu moment. As he jumps backwards into the wall, it wobbles quite badly (as do the parts mounted to it) - obviously just a piece of free-standing plasterboard. (00:09:25)
Revealing mistake: When the white guy is smashing one of the bad guys' head and green blood is coming down, you can see the pipes that shoot it into the head.