Continuity mistake: Dennis walks up to the computer to see the guy claiming to be their father carrying nothing, he puts his empty left hand on the bar, but when the shot switches he is holding a coffee in that hand. In the shot right before the opening credits the coffee is gone again. (00:01:00)AlwaysSunny
Other mistake: In the opening of this episode the screen reads "3:50pm On a Wednesday." When Gino (Frank's brother) is reading the letters meant for Shadynasty, he says "Meet me at the airport, Friday, at 5:00, Terminal C." The gang and Gina then go along to the airport that very afternoon - a Wednesday - to try and meet Shadynasty and get her and Frank back together. And of course she is there, despite it being a Wednesday, not a Friday.
Frank Reynolds: We gotta definitely write a song about how we do not diddle kids!"Do not diddle kids, it's no good diddling kids."
Mac: There is no quicker way for people to think that you are diddling kids than by writing a song about it.