The Calzone - S7-E20
Visible crew/equipment: In the scene where Elaine questions her boyfriend in front of her apartment, look carefully at the end of the conversation. When her boyfriend turns and walks away, you can see where the green screen ends, with the crew members/cameras standing on the set. (00:09:25)
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.