Revealing mistake: When Harvey Bullock and Jim Gordon enter the apartment of the arsonists, as Bullock approaches the bodies, you can see one of the actor's eyes close, despite the fact he is supposed to dead. (00:20:10)
All Happy Families Are Alike - S1-E22
Revealing mistake: When Falcone is attacked with a bazooka, notice how none of the chickens in the cages move a single muscle with the explosion right next to them.
Revealing mistake: The chest of the "dead" girl on the autopsy table moves due to her breathing, and her eyelids move twice. (00:15:20)
Revealing mistake: The glue holding the beard to actor B.D. Wong's (Dr. Hugo Strange) face is always visible.
Answer: Tabitha got her hand sewn back on, Butch didn't.