Cook's Tour - S1-E4
Revealing mistake: After Squad 51 is dispatched to the 'electrocution in a house', while Johnny goes to the garage to turn off the power, Roy waits at the doorway to go inside to the victim. In this interior shot facing the doorway, we see what is supposed to be the brick chimney at the side of the house next door, and the top of that set is visible. Plus the fact that this chimney is not nearly as deep as the one they passed by in the exterior shot.