The Strike - S9-E10
Visible crew/equipment: When Jerry is chasing after Gwen and when he returns to the table, you can see the shadow of the boom mic on the wall. It is most noticeable to the right of the framed picture. (00:20:57)
Visible crew/equipment: After Elaine gets out of the taxi, she starts walking on the sidewalk, before chasing after the taxi once it drives away. The reflection of the filming crew can be seen in the windows of the buildings next to her when she starts walking. (00:06:32)
Chosen answer: George does mention his brother in the episode "The Parking Space". They actually really never mention anything that contradicts the fact he had a brother though, it just isn't mentioned.