party at the opening of the movie

Was this a real party, or a made up party for the movie. The only reason I ask this, most of the people that were at the party have been in Judd Apatow movies, and all seem like they are pretty close. Anyone know? I think its pretty cool how Judd Apatow has made the movies that he has because they are all so realistic and has picked the perfect people to play the parts.