The Sponge - S7-E9
Factual error: During the AIDS walk there is an officer seen several times with a patch "Transit Police, NYC." Not only is the patch completely fictional, it doesn't look anything like the real transit police logo. The Transit Police had already been defunct by the time of this episode.
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.