Heart of Ice - S1-E3
Continuity mistake: When Mr. Freeze's henchman Johnny gets his legs frozen, an ice "bridge" connects the gap between his feet. A few shots later and the connective ice is gone, making it look like he is wearing boots made of ice. (00:05:45 - 00:07:00)
Visible crew/equipment: During the final battle between Duncan and Luther, you can see a crew member holding a boom microphone pole standing on the stack of hay bales in one of the shots. (00:44:10)