The Night of the Infernal Machine - S2-E14
Revealing mistake: Right after Zeno Baroda says, "M'Guigan, I'm going to kill you," he shoots at the door. Before the bullet is discharged, one can see the door is already damaged where the door is about to be shot. Also, one can see the streak (moving from the left to right) of the prop used to cause more damage on the door from the bullet's impact. (00:27:30)
The Night of the Infernal Machine - S2-E14
Continuity mistake: As the toy bear is making its way to Gordon, in the background to the right of the window is a plant on a wooden stand. Next to it is a full length long green curtain with gold tassled fringe at the bottom. Gordon throws the toy bear through the window, but there is no glass breaking. The tall wooden plant stand now is wrapped inside the curtain, and the golden fringe cannot be seen. (00:28:10)