When Eric Beale is pushing the metal rack away from the wall in order to break into their operations center against Corbin's orders, the rack appears to make a metal against concrete noise. But, we can see that the rack is on wheels and the actor is pretending it is hard to move.
When Kensi has neutralised the suspect at the beginning of the episode, she reveals her face. You can clearly see a Lav Mic on her T-Shirt once this is done.