On the DVD commentary, the creators say that they went on location in Philadelphia to shoot many of the exterior shots in the episode. Rob McElhenney says that the red house used as Mac's house actually belongs to his Aunt and Uncle in Philadelphia. He also says that the white house to the right of Mac's house (which can be seen in the long shots) is the house that he grew up in.
Dennis: I'm going to kill him!
Charlie: Wait, wait, wait. What are you going to do, punch him in the face, throw him, going to maybe work the body a little? That's not going to help. No, no, it's not going to help. I'll tell you why. It doesn't unbang your mom.
The classical piece played in the background in the scene when Dennis enters the bar after being phoned by Charlie is Dance of the Sugar Plum Fairy by Pyotr Il'yich Tchaikovsky from the The Nutcracker ballet.