Justin Peters actually isn't wearing pants in the scene where Roger brings Blind Stu back to his apartment.
Production adviser Brad Balonick has the same phone number as writer/producer Justin Peters, just a different area code.
One of the paintings used in the art gallery scene was actually purchased by one of the extras.
The part of Father Muldoon was originally written as a character called "The Rabbi", but Bill Kavanagh's audition convinced the directors to change things up for him.
Oddly enough, Bill Kavanagh actually started taking classes to prepare to convert to Catholicism during shooting.